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Question 1 Report
Question 2 Report
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Question 8 Report
A 400 N box is being pushed across a level floor at a constant speed by a force P of 100 N at an angle of 30.0° to the horizontal, as shown in the the diagram below. What is the coefficient of kinetic friction between the box and the floor?
W = 400 N; P = 100 N; θ = 30o; μ = ?
Frictional force (Fr) = μR (where R is the normal reaction)
The forces acting along the horizontal direction are Fr and Px
∴ Pcos 30° - Fr = ma (Pcos 30° is acting in the +ve x-axis while Fr in the -ve x-axis)
⇒ 100cos 30° - μR = ma
Since the box is moving at constant speed, its acceleration is zero
⇒ 100cos 30° - μR = 0
⇒ 100cos 30o = μR ----- (i)
The forces acting in the vertical direction are W, Py and R
∴ R - Psin 30° - W = 0 (R is acting upward (+ve) while Py and W are acting downward (-ve) and they are at equilibrium)
⇒ R - 100sin 30° - 400 = 0
⇒ R = 100sin 30° + 400
⇒ R = 50 + 400 = 450 N
From equation (i)
⇒ 100cos 30° = 450μ
⇒μ=100cos30°
N = 100cos30°450
= μ = 0.19
Question 9 Report
Question 10 Report
When a water droplet is placed on a freshly cut piece of wood, it spreads out to form a thin layer because the wood is adhesive to water.
Adhesion is the attraction between different substances, in this case, water and wood. Wood is a porous material, meaning it has tiny holes or gaps in its surface. These tiny holes create a large surface area for the water droplet to interact with.
When the water droplet comes into contact with the wood, the adhesive forces between the water molecules and the wood molecules are stronger than the cohesive forces between the water molecules. This causes the water droplet to spread out, trying to maximize its contact with the wood surface.
The spreading out of the water droplet forms a thin layer because the wood surface is not completely smooth. Instead, it has irregularities and imperfections, which allow the water to seep into those gaps and spread out further.
Therefore, when a water droplet is placed on a freshly cut piece of wood, it spreads out to form a thin layer due to the adhesive forces between the water and the wood surface.
Question 11 Report
Which of the following is/are not true about the heat capacity of a substance?
(i) It is an intensive property
(ii) Its S.I unit is \(jK^{-1}\)
(iii) It is an extensive property
(iv) Its S.I unit is \(jkg^{-1}\)
Question 12 Report
Light of wavelength 589 nm in vacuum passes through a piece of fused quartz of index of refraction n = 1.458. What is the frequency of the light in fused quartz?
[Speed of light c = 3 *10^8ms-1]
Question 13 Report
Question 14 Report
Question 15 Report
A beam of light traveling in water is incident on a glass which is immersed in the water. The incident beam makes an angle of \(40^\circ\) with the normal. Calculate the angle of refraction in the glass.
[Refractive index of water = 1.33, Refractive index of glass = 1.5]
Question 16 Report
The number of holes in an intrinsic semiconductor is equal to the number of free electrons.
In an intrinsic semiconductor, the valence band is completely filled with electrons. However, due to thermal energy, some of these electrons can gain enough energy to jump to the conduction band, leaving behind holes in the valence band.
For every electron that moves to the conduction band, a hole is created in the valence band. Since the number of electrons and holes is equal, the number of holes in an intrinsic semiconductor is equal to the number of free electrons.
Therefore, the correct option is: is equal to the number of free electrons.
Question 17 Report
The working of the beam balance is based on the principle of moments.
Moments, also known as torques, are a measure of the turning effect of a force. In the case of the beam balance, it is the moments that help determine the equilibrium or balance of the system.
The beam balance consists of a beam or lever that is supported at a pivot point called the fulcrum. On either end of the beam, there are pans where the objects to be weighed are placed.
When objects of different weights are placed on the pans, the beam becomes unbalanced. This causes the beam to tilt towards the side with the heavier object. However, in order to achieve equilibrium or balance, the moments on both sides of the beam must be equal.
The moment of a force is calculated by multiplying the magnitude of the force by the perpendicular distance from the point of rotation (the fulcrum) to the line of action of the force.
By adjusting the position of the counterweights or by moving the objects on the pans, the moment on each side of the beam can be balanced, resulting in the beam becoming level or horizontal. This indicates that the weights on both sides are equal.
Therefore, the beam balance operates on the principle of moments, where the balance is achieved by equalizing the moments on both sides of the fulcrum.
Question 18 Report
To find the terminal p.d. (potential difference), we need to consider the concept of voltage in a circuit. Voltage is the amount of electrical energy per unit charge provided by a power source, in this case, the battery.
In this problem, we are given:
EMF (electromotive force) of the battery = 24.0 V
Internal resistance of the battery = 1.0 Ω
External resistor = 5.0 Ω
When the battery is connected to the external resistor, a current will flow in the circuit. This current is determined by Ohm's law, which states that the current flowing in a circuit is directly proportional to the voltage applied and inversely proportional to the resistance:
I = V / R
where:
I is the current flowing in the circuit
V is the voltage applied
R is the resistance of the circuit
In this case, the voltage applied is the emf of the battery, and the resistance is the sum of the internal resistance and the external resistor.
We can calculate the current flowing in the circuit:
I = 24.0V / (1.0Ω + 5.0Ω) = 24.0V / 6.0Ω = 4.0A
Now, the terminal p.d. is the voltage drop across the external resistor. We can calculate it using Ohm's law:
V = I * R
Substituting the values:
V = 4.0A * 5.0Ω = 20.0V
Therefore, the terminal p.d. is 20.0V.
Question 19 Report
T=800N; I=50cm=0.5m,
m=10g=0.01kg
fundamental freq: fo
=?
fo
= 121√Tμ
μ =m1
=0.010.5
⇒ fo
=12×0.5
√8000.02
fo
⇒√ 40,000
⇒1st overtone = 2fo
=2×200 = 400Hz
⇒2nd overtone =3fo
=3×200=600Hz
∴3rd over tone= 4fo
=4×200=800Hz
Question 20 Report
An open-tube mercury manometer is used to measure the pressure in a gas tank. When the atmospheric pressure is 101,325 \(P_a\), what is the absolute pressure in \(P_a\) in the tank if the height of the mercury in the open tube is 25 cm higher
Question 21 Report
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Question 23 Report
The correct answer is The electric force is directed from the positive particle to the negative particle.
When a positively charged particle is placed near a negatively charged particle, they exert an attractive force on each other. This force is called the electric force.
According to Coulomb's Law, the electric force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
In this case, the positively charged particle has a positive charge and the negatively charged particle has a negative charge. Since opposite charges attract each other, the electric force between them is attractive.
Therefore, the electric force is directed from the positive particle to the negative particle.
Question 24 Report
Question 25 Report
A good insulator is a material that does not easily allow heat or electricity to pass through it. It acts as a barrier, preventing the flow of heat or electricity. Out of the given options, rubber is a good insulator.
Rubber is made up of long chains of molecules that are closely packed together. These chains do not allow the easy movement of heat or electricity. This means that when heat or electricity tries to pass through rubber, it encounters resistance, making it difficult for it to flow.
In contrast, materials like silver, water, and copper are good conductors rather than insulators.
Silver is an excellent conductor of electricity and heat because its atoms have loosely bound electrons that are free to move. This allows for the easy transfer of heat or electricity throughout the material.
Water is also a good conductor of both heat and electricity. It contains charged particles called ions that can carry electric current. Additionally, water molecules are able to transfer heat through convection.
Copper is widely used in electrical wiring because it is an excellent conductor of electricity. Like silver, its atoms have free electrons that can move easily and transfer electrical energy.
Therefore, rubber is the material that serves as a good insulator, while silver, water, and copper are good conductors of heat and electricity.
Question 26 Report
Question 27 Report
The electrolyte used in the Nickel-Iron (NiFe) accumulator is **potassium hydroxide solution**.
In a Nickel-Iron accumulator, the electrolyte is the substance that allows the flow of electric current between the electrodes. It is essential for the proper functioning of the accumulator.
Potassium hydroxide solution is the ideal electrolyte for the NiFe accumulator due to its properties. It has good electrical conductivity, which means it allows the movement of ions between the positive and negative electrodes, enabling the flow of electrons and facilitating the charging and discharging process.
In addition to good conductivity, potassium hydroxide solution also has other beneficial properties for the NiFe accumulator. It is stable, ensuring a longer lifespan for the accumulator. It is also less prone to self-discharge, meaning the accumulator can retain its charge for a longer period without significant loss.
Therefore, the electrolyte used in the Nickel-Iron (NiFe) accumulator is potassium hydroxide solution.
Question 28 Report
Question 29 Report
The Tungsten filament lamp is a type of incandescent light source.
An incandescent light source works by using electricity to heat a filament inside the bulb until it becomes so hot that it emits light. In a tungsten filament lamp, the filament is made of tungsten, which is a metal that has a very high melting point. This allows the filament to get extremely hot without melting.
When an electric current passes through the filament, it heats up and starts to glow, producing visible light. The light emitted by a tungsten filament lamp is actually a result of the high temperature, which causes the atoms in the filament to vibrate and release energy in the form of light.
Incandescent light sources like tungsten filament lamps have been widely used for many years because they produce a warm, yellowish light that is similar to natural sunlight. However, they are not very energy-efficient, as a significant amount of the electrical energy is converted into heat rather than light.
In recent years, there has been a shift towards more energy-efficient alternatives like LED lamps and fluorescent lamps. LED lamps use a different mechanism to produce light, using a semiconductor that emits light when electric current passes through it. Fluorescent lamps use a gas-filled tube that emits ultraviolet light when electric current flows through it, and this ultraviolet light is then converted into visible light by a phosphor coating inside the tube.
So, in summary, the tungsten filament lamp is the type of incandescent light source among the options given. It works by heating a tungsten filament to a very high temperature, causing it to emit light. However, it is less energy-efficient compared to LED and fluorescent lamps.
Question 30 Report
Question 31 Report
A wave that is both mechanical and longitudinal is sound waves.
Sound waves are created by the vibration of an object, such as a speaker, which causes the air particles around it to vibrate. These vibrations then travel through the air in the form of a wave.
Sound waves are classified as mechanical waves because they require a medium, such as air, water, or solid objects, to travel through. Without a medium, sound waves cannot propagate.
Furthermore, sound waves are classified as longitudinal waves because the particles in the medium vibrate parallel to the direction of the wave. This means that as the sound wave travels, the particles in the medium move back and forth in the same direction as the wave itself.
In contrast, water waves and seismic waves are mechanical waves, but they are not longitudinal. Water waves are categorized as transverse waves because the particles in the water move up and down at right angles to the direction of the wave. Seismic waves, which include earthquake waves, can be both transverse and longitudinal, but typically the primary seismic waves are classified as transverse waves.
Lastly, light waves are not mechanical waves but rather electromagnetic waves. They do not require a medium to travel through and can propagate in a vacuum, unlike sound waves.
Question 32 Report
The property of wave shown in the diagram above is?
Question 33 Report
Surface tension is a property of liquids that arises due to the cohesive forces between the molecules at the surface. It can be thought of as the "skin" or "film" that forms on the surface of a liquid.
Considering the options given:
- Water: Water molecules have strong cohesive forces, allowing them to form hydrogen bonds with each other. As a result, water has relatively high surface tension.
- Mercury: Mercury is a metal with metallic bonding, which is much stronger than the cohesive forces in liquids. As a result, mercury has very high surface tension.
- Oil: Oils typically consist of nonpolar molecules, which have weaker cohesive forces compared to polar molecules like water. Therefore, oil generally has lower surface tension than water.
Based on this information, we can conclude that mercury has the highest surface tension among these liquids.
Question 34 Report
Question 35 Report
In an AC circuit, resonance occurs when the impedance of the circuit is minimum.
Impedance is the total opposition to the flow of alternating current in a circuit, and it consists of two components: resistance (R) and reactance (X).
Reactance can be further divided into two types: inductive reactance (XL) and capacitive reactance (XC).
At resonance, the inductive reactance and the capacitive reactance are equal in magnitude and opposite in sign. This means that their effects cancel each other out, resulting in a minimum total reactance.
Since impedance is the combination of resistance and reactance, when the reactance is at its minimum, the impedance of the circuit is also at its minimum.
So, in summary, resonance occurs in an AC circuit when the impedance is minimum. At resonance, the inductive reactance and the capacitive reactance cancel each other out, resulting in a minimum total reactance and minimum impedance.
Question 36 Report
A parallel plate capacitor separated by an air gap is made of 0.8m2 tin plates and 20 mm apart. It is connected to 120 V battery. What is the charge on each plate?
Take \( \epsilon_o = 8.85 * 10^{-12}\,\mathrm{F\,m^{-1}} \)
Question 37 Report
On a particular hot day, the temperature is 40°C and the partial pressure of water vapor in the air is 38.8 mmHg. What is the relative humidity?
Question 38 Report
A pyrometer thermometer measures temperature from the thermal radiation emitted by objects.
When objects are heated, they emit thermal radiation, which is a form of electromagnetic radiation. This radiation is primarily in the infrared wavelength range. A pyrometer thermometer is specifically designed to measure the intensity of this thermal radiation and convert it into a temperature reading.
The pyrometer thermometer works based on the principle of measuring the amount of thermal radiation reaching the sensor. This is done using a detector that is sensitive to the infrared wavelength range. The detector absorbs the thermal radiation emitted by the object and generates an electrical signal proportional to the intensity of the radiation.
The electrical signal from the detector is then processed by the thermometer's electronics to calculate and display the corresponding temperature. The calibration of the thermometer ensures accurate temperature readings based on the known relationship between the intensity of thermal radiation and temperature.
Pyrometer thermometers are commonly used in industrial applications where contact-based temperature measurement methods are not feasible or accurate enough. They can measure temperatures of objects from a distance without physically touching them, which makes them suitable for measuring high temperatures, moving objects, or objects in hazardous or inaccessible environments.
Therefore, the pyrometer thermometer is the correct option for measuring temperature from thermal radiation emitted by objects.
Question 39 Report
Name the type of equilibrium for each position of the ball
Question 40 Report
The branch of physics that deals with the motion of objects and the forces acting on them is called mechanics.
Mechanics is the foundation of physics that studies how objects move and interact under the influence of forces. It encompasses both the study of the motion of macroscopic objects, such as cars and planets, and the behavior of microscopic particles, such as atoms and molecules.
Mechanics is divided into two main branches:
Therefore, when referring to the branch of physics that specifically focuses on the motion of objects and the forces acting on them, the correct answer is mechanics.
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