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Question 1 Report
Bifocal lens is used to correct the eye defect of
Answer Details
Bifocal lenses are primarily used to correct the eye defect known as presbyopia. As people age, the lens of the eye naturally loses its flexibility, making it difficult to focus on objects that are close up. This condition is known as presbyopia. A bifocal lens is designed with two different optical powers to accommodate this need. The upper part of the lens is usually crafted for distance vision, while the lower segment is designed for near vision tasks, such as reading.
Astigmatism is a different eye condition caused by irregular curvature of the cornea or lens, resulting in blurred or distorted vision at all distances. This condition is typically corrected with cylindrical lenses rather than bifocals.
Hypermetropia, commonly known as farsightedness, is a condition where distant objects can be seen more clearly than near ones. Simple convex lenses are usually used for this correction.
Myopia, or nearsightedness, is a condition where nearby objects are seen clearly, while distant objects appear blurry. Concave lenses are generally used to correct this condition.
In summary, bifocal lenses are specifically designed to address the challenges of focusing at different distances simultaneously, making them ideal for managing presbyopia.
Question 2 Report
The degree of precision of a vernier caliper is
Answer Details
The degree of precision of a vernier caliper is actually the **smallest value** that the vernier scale can measure, which can be considered as the resolution or least count of the instrument. The degree of precision for most standard vernier calipers is 0.01 cm (or 0.1 mm). This means that the caliper can measure dimensions down to a hundredth of a centimeter.
To understand why this is the case, consider the construction of a vernier caliper:
This alignment allows more precise measurements than the main scale alone. If the vernier scale has 10 divisions which coincide over a length equal to 9 divisions on the main scale, then each division of the vernier scale represents an extra 0.01 cm. Therefore, it allows measuring smaller intervals between the main scale markings very precisely.
Thus, you won't find vernier calipers with a degree of precision of 0.005 cm, 0.1 cm, or 1.0 cm as options in standard practice for precise measurement tools.
Question 3 Report
If a charge ion goes through a combined electric field E and magnetic field B, the resultant emergent velocity of the ion is
Answer Details
The resultant emergent velocity of a charged ion moving through combined electric and magnetic fields can be derived from the condition where the electric force equals the magnetic force. This gives us the formula for the velocity v:
q E = qvB
v = EB (q will cancel out)
NOTE: When both fields are present, for the ion to move without deflection, the electric force must equal the magnetic force.
Question 4 Report
When a charged ebonite rod is brought near a charged glass rod, there will be
Answer Details
When a charged ebonite rod is brought near a charged glass rod, there will be attraction. This is because charged objects obey the fundamental principle of electrostatics, which states that opposite charges attract each other while like charges repel each other.
An ebonite rod typically acquires a negative charge when rubbed with fur, as it gains electrons. In contrast, a glass rod usually acquires a positive charge when rubbed with silk, as it loses electrons. Therefore, when these two objects, one negatively charged and the other positively charged, are brought near each other, the opposite charges will attract.
Question 5 Report
The value of R required to make the galvanometer measure voltage up to 40V in the diagram above
Answer Details
In a galvanometer setup intended to measure voltages, you often encounter a configuration known as a voltmeter, where a resistor is added in series with the galvanometer to increase its range of measurement.
The basic principle is that the total resistance of the voltmeter (comprising the galvanometer's resistance and the additional series resistor) allows it to handle a higher voltage by limiting the current that flows through the galvanometer. The maximum voltage (V) that can be measured by the galvanometer is determined by Ohm's Law: V = I * R,
Where:
Assuming the galvanometer has a known internal resistance (G) and a known full-scale current (I_fullscale), the resistance R required in series can be calculated via the formula:
R = (V / I_fullscale) - G
For this solution, you need either the values of G and I_fullscale or their product (G * I_fullscale). Without those exact specifications provided, it would be imprudent to give an exact numeric answer.
However, if this is a typical example and you have a typical galvanometer with a full-scale current of 50 μA and an internal resistance of 500 Ω, you can compute:
R = (40 / 50 x 10^-6) - 500 = 2000 - 500 = 1500 Ω
Therefore, you would need an additional R = 1990 Ω - 1500 Ω = 490 Ω, meaning the closest possible practical value from your choices is 1990 Ω (including the internal resistance).
If the specific parameters of the galvanometer differ, adjust the calculation accordingly, but the general process is as laid out here.
Question 6 Report
The velocity ratio of an inclined plane at 60º to the horizontal is
Answer Details
The concept of an inclined plane is all about simplifying the forces involved in moving or holding a load. The **velocity ratio (VR)** for an inclined plane is defined as the ratio of the distance moved by the effort to the distance moved by the load. This can also be expressed in terms of the lengths involved in the triangle made by the inclined plane.
For an inclined plane placed at an angle **θ** to the horizontal, the velocity ratio is given by the formula:
VR = 1/sin(θ)
Given that the inclined plane is at an angle of **60º**:
First, find the sine of 60º:
sin(60º) = √3/2 (approximately 0.866)
Now, substitute this value into the formula for VR:
VR = 1/sin(60º) ≈ 1/0.866 ≈ 1.155
The **velocity ratio** for an inclined plane at **60º** to the horizontal is **approximately 1.155**.
Question 7 Report
The value of R in the above circuit to make the galvanometer measure 2A is
Answer Details
Given: Ig = 50mA = 0.05A, I to be measured = 2A, r = 2Ω , Is = I - Ig = 2 - 0.05 = 1.95A
Shunt(R) = IgIs x r
R = 0.051.95 x 10 = 0.2564Ω
Question 8 Report
The charge of magnitude 1.6 x 10 −19 C is placed in a uniform electric field of intensity 1200Vm−1 . Calculate its acceleration, if the mass of the charge is 9.1 x 10−31 kg
Answer Details
To calculate the acceleration of a charge in an electric field, we start by determining the force acting on the charge. The force \( F \) experienced by a charge \( q \) in a uniform electric field \( E \) is given by the equation:
F = q * E
We are given:
Substituting these values into the equation for force:
F = 1.6 x 10-19 C * 1200 V/m
This results in:
F = 1.92 x 10-16 N
Next, we use Newton’s second law of motion to find the acceleration \( a \) of the charge. This law is given as:
F = m * a
Rearranging for \( a \), we have:
a = F / m
We know:
Substituting these values in the equation for acceleration:
a = \(\frac{1.92 x 10^{-16} N}{9.1 x 10^{-31} kg}\)
Calculating the above expression gives:
a ≈ 2.11 x 1014 ms-2
Therefore, the acceleration of the charge is approximately 2.11 x 1014 ms-2.
Question 9 Report
Pilots uses aneroid barometer to know the height above sea level because
Answer Details
Aneroid barometers are compact and lightweight, making them suitable for use in aircraft where space and weight are critical considerations. They provide a reliable measurement of altitude based on changes in atmospheric pressure.
Question 10 Report
Using the diagram above, the effective force pushing it forward at an angle 60º is
Answer Details
To determine the effective force pushing the object forward at an angle of 60º, we need to resolve the given force into its components. Specifically, we are interested in the horizontal component of the force, as this is the part that effectively pushes the object forward.
The general formula to calculate the horizontal component of a force (Fx) when the force is applied at an angle (θ) is:
Fx = F * cos(θ)
Where:
Assuming the magnitude of the force applied (F) is 50N, then the effective forward force can be calculated as follows:
Fx = 50N * cos(60º)
Using the trigonometric value:
cos(60º) = 0.5
Therefore:
Fx = 50N * 0.5
Fx = 25N
Hence, the effective force pushing it forward at an angle of 60º is 25.00N. Therefore, the correct answer is 25.00N.
Question 11 Report
A blacksmith heated a metal whose cubic expansivity is 3.9 x 10−6 K−1 . Calculate the area expansivity.
Answer Details
To find the area expansivity of a metal when given its cubic expansivity, you should understand the relationship between linear, area, and cubic expansivity.
Cubic expansivity (\( \beta \)) is defined as the fractional change in volume per change in temperature, and is given by the formula:
\[ \Delta V = \beta V \Delta T \]
Area expansivity (\( \alpha_{A} \)) corresponds to the fractional change in area per change in temperature and can be derived from the linear expansivity (\( \alpha \)). The relationship between these expansivities is as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = 2 \times \text{Linear Expansivity (\( \alpha \))} \]
The cubic expansivity (\( \beta \)) is related to the linear expansivity by:
\[ \text{Cubic Expansivity (\( \beta \))} = 3 \times \text{Linear Expansivity (\( \alpha \))} \]
Thus, based on these relationships, we can express the area expansivity in terms of the cubic expansivity:
\(\text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times \text{Cubic Expansivity (\( \beta \))}
Given that the cubic expansivity \( \beta \) is \( 3.9 \times 10^{-6} \, \text{K}^{-1} \):
The area expansivity can be calculated as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times 3.9 \times 10^{-6} \, \text{K}^{-1} = 2.6 \times 10^{-6} \, \text{K}^{-1} \]
Therefore, the **correct answer** is **2.6 x 10^{-6} K^{-1}**.
Question 12 Report
A monochromatic light is one that
Answer Details
A monochromatic light is one that has a single wavelength or color. This means that it consists of light waves that all have the same frequency, resulting in a uniform appearance without any variation.
Question 13 Report
When a bus is accelerating, it must be
Answer Details
When a bus is accelerating, it is primarily changing its velocity. This is because velocity is a vector quantity, which means it includes both the speed and the direction of the object's movement. Acceleration refers to any change in this velocity. Therefore, the bus could be increasing its speed, decreasing its speed (which is also known as deceleration), or changing its direction. All these aspects involve a change in velocity.
Let's break it down further:
Changing its Speed: If the bus is speeding up or slowing down, it results in a change in the magnitude of its velocity, contributing to acceleration.
Changing its Direction: Even if the bus maintains a constant speed, if it changes direction (like taking a turn), its velocity is altered because direction is a part of velocity. This results in acceleration.
Changing its Position: While a change in position happens during acceleration, it is not the defining feature of acceleration. An object can change its position even if it is moving with constant velocity and not accelerating.
So, the key component here for acceleration is the change in velocity, which encompasses changes in speed, direction, or both.
Question 14 Report
A hydrometer of mass y kg and volume 2y x 10−5 m3 floats in a fluid with 20% of its volume above the fluid, what is the density of the fluid?
Answer Details
To find the density of the fluid, we need to apply the principle of floatation, which states that the weight of the fluid displaced by the submerged part of the object is equal to the weight of the object. Let's walk through the steps:
Step 1: Understand the volume submerged
The hydrometer has a total volume of 2y x 10-5 m3. It floats with 20% of its volume above the fluid. Hence, 80% of its volume is submerged in the fluid.
Submerged Volume, Vsub = (0.80) x (2y x 10-5 m3) = 1.6y x 10-5 m3
Step 2: Apply the principle of floatation
The weight of the fluid displaced equals the weight of the hydrometer.
Weight of hydrometer = Mass x Gravity = y kg x g (where g is the acceleration due to gravity). For the purpose of calculations, g can be considered as 9.81 m/s2.
Weight of displaced fluid = Density of fluid (ρfluid) x Submerged Volume x g
According to the principle of floatation:
y x g = ρfluid x 1.6y x 10-5 m3 x g
g is common on both sides and can be canceled out:
y = ρfluid x 1.6y x 10-5
Step 3: Solving for the density of the fluid
ρfluid = y / (1.6y x 10-5)
The y on both numerator and denominator cancels out:
ρfluid = 1 / (1.6 x 10-5)
ρfluid = 6.25 x 104 kg/m3
Thus, the density of the fluid is 6.25 x 104 kg/m3.
Question 15 Report
Calculate the value of electric field intensity due to a charge of 4μC if the force due to the charge is 8N
Answer Details
To calculate the electric field intensity due to a charge, we need to use the formula:
Electric Field Intensity (E) = Force (F) / Charge (q)
In this problem, we are given that the force (F) is 8 Newtons (N) and the charge (q) is 4 microcoulombs (μC). First, we need to convert the charge from microcoulombs to coulombs:
1 microcoulomb (μC) = 1 x 10-6 coulombs (C)
Therefore, 4 μC = 4 x 10-6 C.
Now we can use the formula to find the electric field intensity:
E = F / q
E = 8 N / (4 x 10-6 C)
E = 8 / 4 x 106
E = 2 x 106
Thus, the value of the electric field intensity is 2 x 106 N/C.
Question 16 Report
The quantity of heat required to melt ice of 0.2 kg whose specific latent heat is 3.4 x 105 J/Kg is
Answer Details
To determine the quantity of heat required to melt ice, we use the formula for latent heat:
Q = m × L,
where:
For this problem, we have:
Now, substitute these values into the formula:
Q = 0.2 kg × 3.4 × 105 J/kg
Calculate the product:
Q = 0.68 × 105 J
To express this in standard scientific notation, it can be rewritten as:
Q = 6.8 × 104 J
Thus, the quantity of heat required to melt 0.2 kg of ice is 6.8 × 104 J.
Question 17 Report
A wheelbarrow inclined at 60º to the horizontal is pushed with a force of 150N. What is the horizontal component of the applied force
Answer Details
When you push a wheelbarrow inclined at an angle to the horizontal, the applied force can be divided into two components: a **horizontal component** and a **vertical component**. To find the horizontal component of the force, you need to use the concept of resolving vectors.
The force of 150N is acting at an angle of 60º to the horizontal. The horizontal component of this force can be calculated using the cosine of the angle. The formula to determine the horizontal component \( F_{\text{horizontal}} \) is given by:
Fhorizontal = Fapplied \times \cos(\theta)
Where:
Substitute the values into the formula:
Fhorizontal = 150N \times \cos(60º)
We know that \(\cos(60º)\) equals 0.5.
Therefore:
Fhorizontal = 150N \times 0.5 = 75N
Thus, the **horizontal component** of the applied force is 75N.
Question 18 Report
Infra-red thermometers work by detecting the
Answer Details
Infra-red thermometers work by detecting the radiation from the body and converting it to temperature. These thermometers are designed to measure the infrared radiation, also known as heat radiation, emitted by objects. All objects with a temperature above absolute zero emit infrared radiation. The thermometer's sensor captures this radiation and converts it into an electrical signal that can be read as a temperature measurement. This method allows for quick, non-contact temperature readings, which is why infrared thermometers are often used in medical settings, industrial applications, and more.
Question 19 Report
Using the diagram above, calculate the relative density of x, if the density of methanol is 800kgm−3
Answer Details
density of methanol = 800kgm−3 → 0.8gcm−3
At equilibrium, the density of methanol = the density of liquid x
ρ x h x g = ρ x x hx x g
0.8 x 7.1 = ρ x x 14.2
ρ x = 0.8×7.114.2 = 0.4gcm−3
∴ , the relative density of liquid x = 0.4
Relative density of X = density of liquid xdensity of methanol = 0.40.8 = 0.5
Question 20 Report
The simple form of the lead acid accumulator often has a negative pole of
Answer Details
The simple form of the lead acid accumulator often has a negative pole of lead plate. In a lead-acid battery, the key components include two electrodes and an electrolyte. The **negative pole**, also known as the cathode during discharge, is typically made of **lead (Pb)**, which is in the form of a **lead plate**. When the battery is in use or discharging, this lead reacts with sulphuric acid (the electrolyte) to create lead sulfate.
To break it down further:
Thus, by analyzing the composition and reactions within a lead-acid battery, it is clear that the **negative pole** is made from a **lead plate**.
Question 21 Report
A load of 300N is to be lifted by a machine with a velocity ratio of 2 and an efficiency of 60%. What effort will be applied to lift the load?
Answer Details
To determine the effort needed to lift a load using a machine, we first need to understand some key concepts: **Load**, **Effort**, **Velocity Ratio** (VR), and **Efficiency**.
1. **Load** is the force or weight that needs to be lifted by the machine. In this case, the load is 300N.
2. **Velocity Ratio (VR)** is the ratio of the distance moved by the effort to the distance moved by the load. Given here as 2.
3. **Efficiency** of a machine is expressed as a percentage and is the ratio of the useful work output to the input work done by the effort. Here, the efficiency is 60% or 0.60 as a decimal.
The formula to calculate the **Effort** is derived from the relationship between these factors:
\[ \text{Efficiency} = \frac{\text{Mechanical Advantage (MA)}}{\text{Velocity Ratio (VR)}} \]
Where:
\[ \text{Mechanical Advantage (MA)} = \frac{\text{Load}}{\text{Effort}} \]
From the above, we have:
\[ \text{MA} = \text{VR} \times \text{Efficiency} \]
Replacing with the given values:
\[ MA = 2 \times 0.60 = 1.2 \]
Now, calculate the **Effort** using the relation:
\[ \text{Effort} = \frac{\text{Load}}{\text{MA}} \]
\[ \text{Effort} = \frac{300N}{1.2} = 250N \]
Therefore, the **Effort** needed to lift the load is 250N.
Question 22 Report
An ideal transformer has
Answer Details
An ideal transformer is a hypothetical concept used in electrical engineering to simplify the analysis of real transformers. In an ideal transformer, several assumptions are made to avoid losses and inefficiencies. Here's what an ideal transformer has:
No flux leakage: In an ideal transformer, it is assumed that all the magnetic flux generated in the primary coil is perfectly linked with the secondary coil. This means there is no flux leakage. This assumption ensures maximum efficiency, as all the energy is transferred from the primary to the secondary coil without losses.
Let's briefly discuss the other concepts to understand why they don't pertain to an ideal transformer:
Maximum primary resistance: In an ideal transformer, the resistance of the windings is assumed to be zero. If the primary has maximum resistance, it would result in power loss due to the resistance, contradicting the idea of an ideal transformer.
Hysteresis: This refers to the energy loss that happens in the core material due to the cyclic magnetization and demagnetization processes. An ideal transformer assumes there is no hysteresis loss, meaning the core material does not absorb any energy during these cycles.
Eddy current: These are loops of electric current induced within conductors by a changing magnetic field, which can cause significant energy loss. In an ideal transformer, it is assumed that there are no eddy currents, hence no energy loss due to this effect.
In summary, an ideal transformer is characterized by having no flux leakage, and it assumes that there are no losses due to resistance, hysteresis, or eddy currents. This makes the ideal transformer a perfect, lossless device for the purposes of theoretical analysis.
Question 23 Report
An electron falls from an energy level of -5.44eV to another energy level, E. If the emitted photon is of wavelength 5.68 x 10−6 m, calculate the energy change. [ Plank's constant = 6.63 x 10−34 Js, emitted radiation speed = 3.0 x 108 ms−1 ]
Answer Details
To find the energy change when an electron falls from one energy level to another, we need to calculate the energy of the emitted photon. This energy can be found using the formula:
E = hν or E = hc/λ
where:
Substitute these values into the equation:
E = (6.63 x 10-34 Js) * (3.0 x 108 ms-1) / (5.68 x 10-6 m)
First, calculate the numerator:
(6.63 x 10-34) * (3.0 x 108) = 1.989 x 10-25 J·m
Then, divide by the wavelength:
E = 1.989 x 10-25 J·m / 5.68 x 10-6 m = 3.5 x 10-20 J
Therefore, the energy change when the electron falls is approximately 3.5 x 10-20 J.
Checking the options provided, the closest value is 3.49 x 10-20 J.
Question 24 Report
The efficiency of a cell with internal resistance of 2Ω supply current to a 6Ω resistor is
Answer Details
To determine the efficiency of a cell with an internal resistance of 2 Ω while supplying current to a 6 Ω resistor, we can use the concept of power dissipation. Efficiency in this context is the ratio of the power delivered to the external resistor to the total power supplied by the cell. It can be calculated using the formula:
Efficiency (%) = (Power across load resistor / Total power output by cell) × 100
Let's break it down step by step:
The efficiency of the cell when supplying current to a 6 Ω resistor with an internal resistance of 2 Ω is 75%.
Question 25 Report
Calculate the quantity of heat for copper rod whose thermal capacity is 400Jk−1 for a temperature change of 60ºC to 80ºC
Answer Details
To calculate the quantity of heat absorbed or released by a substance, we can use the formula:
Q = C × ΔT
where:
Given:
First, calculate the change in temperature:
ΔT = Final temperature - Initial temperature = 80°C - 60°C = 20°C
Now, substitute the values into the formula to find the quantity of heat:
Q = 400 J/°C × 20°C
Calculate the answer:
Q = 8000 J
Since the options provided are in kilojoules (KJ), we need to convert joules (J) to kilojoules (1 KJ = 1000 J):
Q = 8000 J ÷ 1000 = 8 KJ
Therefore, the quantity of heat for the copper rod, given the specified conditions, is 8 KJ.
Question 26 Report
Use the diagram above to answer the question that follows
The diagram above is
Answer Details
The diagram in the image represents the urinary system, as indicated by the correct answer. The urinary system includes the kidneys, ureters, bladder, and urethra, which are responsible for filtering blood and excreting waste in the form of urine.
Kidneys – Filter waste and excess fluids from the blood to form urine.
Ureters – Tubes that carry urine from the kidneys to the bladder.
Urinary Bladder – Stores urine before it is expelled from the body.
Urethra – A tube that allows urine to exit the body.
This system plays a crucial role in maintaining the body's fluid balance and removing waste products.
Question 27 Report
The device for measuring the angle of dip is
Answer Details
The device used for measuring the angle of dip is the dip circle.
Let me explain this in simple terms:
The angle of dip, also known as the magnetic inclination, is the angle made by the Earth's magnetic field lines with the horizontal plane. It varies depending on where you are on the Earth's surface. In some places, magnetic field lines are nearly vertical, while in others they are more horizontal.
A dip circle is a specialized scientific instrument used to measure this angle. It usually consists of a magnetic needle that is free to rotate in the vertical plane.
When using a dip circle, you align it so that its plane is parallel to the direction of the Earth's magnetic field. Then, you read the angle at which the magnetic needle stabilizes. This is the angle of dip. The instrument's mechanism allows for accurate measurement of this angle by compensating for any external influences or inclinations.
Question 28 Report
The total number of ATP produced during glycolysis is
Answer Details
During the process of glycolysis, a single glucose molecule is broken down into two molecules of pyruvate. During this metabolic pathway, there is a net gain of adenosine triphosphate (ATP) molecules. To understand how many ATP molecules are produced, let's break it down step by step.
1. **Initial ATP Investment:** Glycolysis initially requires an investment of 2 ATP molecules to phosphorylate glucose and convert it into a more reactive form during the early stages of the glycolytic pathway.
2. **ATP Production:** As glycolysis progresses, a total of 4 ATP molecules are produced. This occurs in the later steps of the pathway where adenosine diphosphate (ADP) is phosphorylated to form ATP. This is known as substrate-level phosphorylation.
3. **Net ATP Gain:** To find out the net gain of ATP through glycolysis, simply subtract the initial ATP investment from the total ATP produced:
Net ATP = Total ATP produced - Initial ATP investment
Net ATP = 4 ATP - 2 ATP
Net ATP = 2 ATP
Thus, the net total number of ATP produced during glycolysis is 2 molecules.
Question 29 Report
Calculate the magnetic force on an electron in a magnetic field of flux density 10T, with a velocity of 3 x 107 m/s at 60º to the magnetic field (e = 1.6 x 10−19 C)
Answer Details
The magnetic force on an electron in a magnetic field (F) = q v Bsinθ
B = 10T, q = 3 x 107 m/, θ = 60º and q = 1.6 x 10−19 C
F = 1.6 x 10−19 x 3 x 107 x 10 x sin 60º ≊ 4.162 × 10−11 N
Question 30 Report
The dimension of power is
Answer Details
The dimension of power in physics is expressed in terms of the base units of mass (M), length (L), and time (T). Power is the rate at which work is done or energy is transferred over time, and it has the unit of watt (W) which is equivalent to one joule per second.
To derive the dimension of power:
1. Work has the dimension of energy, which is force applied over a distance. The dimension of work (or energy) is M L2 T-2 because force has the dimension M L T-2 and distance adds another L.
2. Since power is work done per unit time, you would divide the dimension of work by time (T).
Thus, the dimensional formula for power is:
M L2 T-3
Question 31 Report
In a Hare's apparatus, the height of water and a liquid X are 0.3m and 0.5m respectively. The relative density of x is?
Answer Details
For Hare's apparatus
Relative density = hwhl
Given: height of liquid = 0.5cm, height of water = 0.3cm
Relative density = 0.30.5 = 0.6
Question 32 Report
In voltage measurement, the potentiometer is preferred to voltmeter because it
Answer Details
In voltage measurement, a **potentiometer is preferred to a voltmeter** primarily because it **consumes negligible current**. Let me explain this in simpler terms:
A **voltmeter** is an instrument used to measure the potential difference (voltage) across two points in an electrical circuit. However, when a voltmeter is connected, it draws a small amount of current from the circuit to make the measurement, which can slightly alter the voltage being measured. This is particularly an issue in high-resistance circuits where even a small current draw can significantly affect the measurement.
On the other hand, a **potentiometer** is a device designed to measure voltage by comparing it with a known reference voltage without drawing current from the circuit under test. It comes into balance at a point where no current flows through it, ensuring that the measurement is not influenced by the potentiometer itself. This makes it a non-invasive method of measuring voltage, which is particularly useful for precise measurements in sensitive circuits.
Here’s a brief explanation about why the other options listed are less relevant:
Therefore, the key advantage of the potentiometer is its **ability to measure voltage without altering the circuit**, which stems from its negligible current consumption. This **ensures more accurate and reliable measurements** in many applications.
Question 33 Report
Answer Details
To solve this problem, we need to understand the relationship between pressure, volume, and temperature of a gas. The relevant law here is the **Combined Gas Law**, which is expressed as:
(P1 * V1) / T1 = (P2 * V2) / T2
Where:
In the given problem:
Applying the Combined Gas Law:
(P1 * V1) / 300 = (2 * P1 * V2) / 400
Simplifying this equation:
V1/300 = 2V2/400
Multiply both sides by 400 to clear the fraction:
400 * V1 / 300 = 2 * V2
Which further simplifies to:
(4/3) * V1 = 2 * V2
Dividing both sides by 2:
(2/3) * V1 = V2
This shows that the final volume, V2, is **2/3 of the initial volume, V1**. Therefore, the volume of the gas will **decrease by 1/3**.
Question 34 Report
The food nutrient with the highest energy value is
Answer Details
Fat is the food nutrient with the highest energy value, providing 9 calories per gram, while carbohydrates and proteins provide 4 calories per gram.
Fat is the body's most concentrated source of energy, providing more than twice as much potential energy as carbohydrates or proteins.However, carbohydrates burn fastest in metabolism. Fats are a type of lipid. Lipids are a group of organic compounds that are insoluble in water but soluble in organic solvents. Fats are solid at room temperature, while oils are liquid at room temperature.
Therefore, the correct answer is option C.
Question 35 Report
Photometer is used to measure
Answer Details
A photometer is an instrument designed to measure the intensity of light. It is used to determine how much light is received over a particular area. Photometers are vital in various fields such as photography, astronomy, and laboratory science for ensuring that light levels are appropriate for specific applications.
The device operates by assessing the brightness or illumination coming from a light source and comparing it with a standard light. The measurement can be displayed in different units such as lumens or lux, depending on the context of the measurement.
While photometers are focused on the intensity of light, they do not measure kinetic energy of liberated electrons, the frequency of light, or the wavelength of light. These quantities are measured using other specialized instruments, such as spectrometers or frequency analyzers.
Question 36 Report
A refrigerator uses 150W. If it is kept on for 336 hours non-stop, what is the energy consumed in KWh?
Answer Details
To calculate the energy consumption of an appliance, you can use the formula:
Energy (in KWh) = Power (in kW) × Time (in hours)
First, convert the power rating of the refrigerator from watts (W) to kilowatts (kW). Since 1 kW is equal to 1000 W, you can convert 150W to kilowatts by dividing by 1000:
150 W = 0.150 kW
Next, calculate the energy consumed over the period the refrigerator is kept on, which is 336 hours. Use the formula:
Energy = 0.150 kW × 336 hours
Now, perform the multiplication:
Energy = 50.40 kWh
Therefore, when the refrigerator is kept on for 336 hours non-stop, it consumes 50.40 kWh of energy. This is the correct choice.
Question 37 Report
The power of a convex lens of focal length 20cm is
Answer Details
The power of a lens is a measure of its ability to converge or diverge light. It is defined as the reciprocal (or inverse) of the focal length of the lens. The formula for calculating the power (P) of a lens in diopters (D) is given by:
P = 1/f
where:
In this case, the focal length given is 20 cm. To apply the formula, we first need to convert this focal length into meters because the diopter is the reciprocal of the focal length in meters:
f = 20 cm = 0.20 m
Now, substitute the focal length in meters into the formula for power:
P = 1 / 0.20
P = 5.00 D
Thus, the power of the convex lens is 5.00 diopters. This indicates that the lens is capable of converging light at a distance of 5.00 meters.
Question 38 Report
The part of the inner ear that is responsible for hearing is
Answer Details
The part of the inner ear that is responsible for hearing is the cochlea.
The inner ear is a complex structure, and each of its components serves different functions. Let me break it down further:
Thus, the cochlea is the crucial component of the inner ear responsible for converting sound vibrations into nerve signals, making it central to the process of hearing.
Question 39 Report
Calculate the depth of a swimming pool if the apparent depth is 10cm. ( Refractive index of water = 1.33 )
Answer Details
To calculate the real depth of a swimming pool given the apparent depth, we can use the concept of refraction of light. When light passes from one medium to a denser medium, it bends towards the normal. This bending effect causes objects submerged in water to appear closer to the surface than they actually are. The formula to relate these depths is given by:
Real Depth = Apparent Depth × Refractive Index
Given the problem:
Using the formula:
Real Depth = 10 cm × 1.33
Calculating the above:
Therefore, the depth of the swimming pool is 13.3cm.
Question 40 Report
Two capacitors of 0.0003μF and 0.0006μF are connected in series, find their combined capacitance.
Answer Details
When capacitors are connected in series, the formula to find their combined capacitance \(C_{\text{total}}\) is given by:
\[ \frac{1}{C_{\text{total}}} = \frac{1}{C_1} + \frac{1}{C_2} \]
where \(C_1\) and \(C_2\) are the capacitances of the individual capacitors. In this case, \(C_1 = 0.0003 \, \mu\text{F}\) and \(C_2 = 0.0006 \, \mu\text{F}\).
First, calculate the reciprocal of each capacitance:
\[ \frac{1}{C_1} = \frac{1}{0.0003} \]
\[ \frac{1}{C_2} = \frac{1}{0.0006} \]
Calculating each value:
\[ \frac{1}{0.0003} = \frac{10^6}{3} \] and \[ \frac{1}{0.0006} = \frac{10^6}{6} \]
Now, add these values together:
\[ \frac{1}{C_{\text{total}}} = \frac{10^6}{3} + \frac{10^6}{6} = \frac{10^6 \times 2}{6} + \frac{10^6 \times 1}{6} = \frac{10^6 \times 3}{6} = \frac{10^6}{2} \]
Finally, take the reciprocal of the resulting value to find \(C_{\text{total}}\):
\[ C_{\text{total}} = \frac{2}{10^6} = 0.0002 \, \mu\text{F} \]
So, the combined capacitance of the two capacitors in series is 0.0002 μF.
 
                    
 
                    
                    
                    
                 
                    
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