JAMB UTME - Physics - 2018
Question 1 Report
A man walks 1km due east and then 1 km due north. His displacement is
Answer Details
The man first walks 1 km due east, which means he has moved 1 km horizontally to the right of his starting point. Then, he walks 1 km due north, which means he has moved 1 km vertically upwards from his previous position. To find his displacement, we need to draw a straight line from his starting point to his final position, which represents the shortest distance between the two points. This line is called the displacement vector. We can use the Pythagorean theorem to calculate the length of the displacement vector. The horizontal and vertical distances are the two legs of a right-angled triangle, and the hypotenuse is the length of the displacement vector. Using the Pythagorean theorem, we get: displacement = √((1 km)^2 + (1 km)^2) = √2 km The direction of the displacement vector is the angle between the displacement vector and the due north direction. We can find this angle using trigonometry. The tangent of the angle is the ratio of the horizontal distance to the vertical distance: tan(θ) = (1 km) / (1 km) = 1 Using a calculator, we can find that the angle is 45°. Therefore, the man's displacement is √2 km in the direction N 45° E. So, the correct answer is √2km N 45°E.
Question 2 Report
Which of the following is the dimension of pressure
Answer Details
The dimension of pressure is ML-1T-2 Pressure is defined as the force per unit area. This means that pressure is dependent on the force applied and the area over which it is applied. The unit of force is measured in Newtons (N), and the unit of area is measured in square meters (m2). Therefore, the unit of pressure is N/m2, which is also known as Pascals (Pa). To determine the dimension of pressure, we need to break down the units into their fundamental dimensions of mass (M), length (L), and time (T). Force is measured in N, which is kg m/s2. Area is measured in m2, which is L2. Therefore, the dimension of pressure can be calculated as (kg m/s2)/(L2), which simplifies to ML-1T-2.
Question 3 Report
One of the features of the fission process is that
Answer Details
The fission process refers to the splitting of an atomic nucleus into two or more smaller nuclei. One of the key features of the fission process is that it can lead to a chain reaction, where the neutrons released during fission can go on to trigger additional fission reactions. This chain reaction can produce a large amount of energy, as is the case in nuclear power plants and nuclear weapons.
Another feature of the fission process is that it typically produces radioactive products. These products can remain radioactive for a long time, which is why there are concerns about the safe disposal of nuclear waste.
Additionally, the fission process typically releases neutrons, which can go on to cause further fission reactions. This neutron release is an important aspect of the chain reaction mentioned earlier.
Finally, the fission process is accompanied by a small loss of mass, which is converted into energy according to Einstein's famous equation E=mc². This loss of mass is what allows the large amount of energy to be released during a fission reaction.
Question 4 Report
A resistor connected to a 12V battery draws a current of 2A. The energy dispatched in the resistor in 5 minutes is ___.
Answer Details
To calculate the energy dispatched in the resistor, we need to use the formula:
Energy = Power x Time
Where Power is the amount of electrical power consumed by the resistor, and is equal to the product of the voltage across the resistor and the current flowing through it:
Power = Voltage x Current
In this case, the voltage across the resistor is 12V, and the current flowing through it is 2A. Therefore, the power consumed by the resistor is:
Power = 12V x 2A = 24W
Now, we can substitute this value of power along with the given time of 5 minutes into the formula for energy:
Energy = 24W x 5min x 60s/min = 7,200J
Therefore, the energy dispatched in the resistor in 5 minutes is 7,200J.
is the correct answer.
Question 5 Report
For what values of F and ? will the forces shown in the diagram below be in equilibrium.
Answer Details
Resolve vertically, 40cos? = 20, ? = 60o
Resolve horizontally, f = 40sin? = 40sin60o
= 40(?32 )
= 20?3 N
Resolve horizontally, f = 40sin? = 40sin60o
= 40(?32 )
= 20?3 N
Question 6 Report
Natural radioactivity consists of the emission of
Answer Details
Radioactive decay releases different types of energetic emissions. The three most common types of radioactive emissions are alpha particles, beta particles, and gamma rays.
Question 7 Report
What flows to the earth by connecting the conductor to the earth?
Answer Details
When a conductor is connected to the earth, electrons flow to the earth. Electrons are negatively charged particles that are present in all conductors. When a conductor is connected to the earth, it creates a path for electrons to flow from the conductor to the earth, which helps to balance the electric potential and prevent the buildup of electric charge. This flow of electrons is known as grounding and is an important safety measure in electrical systems.
Question 8 Report
The product of force and time is?
Answer Details
The product of force and time is known as impulse.
Impulse can be defined as the change in momentum that an object experiences as a result of a force being applied to it over a period of time. In simpler terms, impulse is the "push" that an object receives from a force acting on it for a certain amount of time. The more force applied, or the longer the time the force is applied, the greater the impulse and the greater the change in momentum of the object.
It's important to note that impulse is a vector quantity, meaning it has both magnitude and direction. Impulse is a measure of the ability of a force to cause an object to change its velocity, and can be used to explain many phenomena in physics, such as why a heavy object is harder to stop than a lighter one, or why a soccer ball changes direction when it is kicked.
Question 9 Report
A positively charged rod X is brought near an uncharged metal sphere Y and is then touched by a finger with X still in place. When the finger is removed, the result is that Y has
Answer Details
Question 10 Report
A solid weighs 45N and 15N respectively in air and water. Determine the relative density of the solid
Answer Details
The relative density of a substance is defined as the ratio of its density to the density of a reference substance, usually water at 4 degrees Celsius. In this problem, we can use the principle of buoyancy to determine the density of the solid. When an object is submerged in a fluid, it experiences an upward force called the buoyant force, which is equal to the weight of the fluid displaced by the object. If the object is less dense than the fluid, it will float, and if it is more dense, it will sink. We are given that the solid weighs 15 N in water, which means it displaces 15 N of water. The weight of the water displaced is equal to the buoyant force on the solid, which is equal to the weight of the solid when it is completely submerged in water. Therefore, the weight of the solid when it is completely submerged in water is 15 N. We are also given that the weight of the solid in air is 45 N. The difference between the weight of the solid in air and water is equal to the weight of the water displaced, which is 30 N. This means that the volume of water displaced by the solid is 30/9.8 = 3.06 L (since the density of water is 1000 kg/m^3 or 9.8 N/L). The relative density of the solid is equal to its density divided by the density of water. We can find the density of the solid by dividing its weight in air by its volume: Density of solid = Weight of solid in air / Volume of solid Density of solid = 45 N / (45 N - 15 N) [since weight of displaced water is 15N] Density of solid = 45 N / 30 N Density of solid = 1.5 N/L Therefore, the relative density of the solid is: Relative density = Density of solid / Density of water Relative density = 1.5 N/L / 1000 N/L Relative density = 0.0015 So the answer is 0.33 (rounded to two decimal places).
Question 11 Report
When a known standard resistor of 2.0 is connected to the 0.0cm end of a meter bridge, the balance point is found to be at 55.0cm. What is the value of the unknown resistor?
Answer Details
A meter bridge is an instrument used to measure the unknown resistance of a conductor. The meter bridge consists of a long resistance wire AB of uniform cross-sectional area and a battery of known voltage connected across its ends. A galvanometer is connected across a point C on the wire, which is called the null point or balance point.
When a known standard resistor of 2.0 ohms is connected to the 0.0cm end of the meter bridge wire, the balance point is found to be at 55.0cm. This means that the resistance of the unknown resistor is equal to the resistance of a portion of the meter bridge wire between the 0.0cm and the 55.0cm point.
To find the value of the unknown resistor, we can use the principle of the Wheatstone bridge, which states that the ratio of the resistances in the two arms of a balanced bridge is equal.
Let R be the resistance of the unknown resistor, then we have:
R/2.0 = (100 - 55.0)/55.0
Simplifying this expression, we get:
R = 2.0 x (100 - 55.0)/55.0
R = 1.64 ohms
Therefore, the value of the unknown resistor is 1.64 ohms.
Question 12 Report
The differences observed in solids, liquids and gases may be accounted for by
Answer Details
The differences observed in solids, liquids, and gases can be accounted for by the spacing and forces acting between the molecules.
In a solid, the molecules are packed closely together, so they have a fixed shape and volume. The intermolecular forces are strong enough to keep the molecules in a fixed position relative to one another.
In a liquid, the molecules are still close together, but they are free to move around each other. The intermolecular forces are weaker than in a solid, so the molecules can slide past one another, giving the liquid its ability to flow and take the shape of its container.
In a gas, the molecules are widely spaced and are in constant motion. The intermolecular forces are very weak, so the molecules are free to move around and fill any available space. Gases have no fixed shape or volume.
So, the differences observed in solids, liquids, and gases can be explained by the spacing and forces acting between the molecules. It's not about their relative masses, melting points, or the different molecules in each of them.
Question 13 Report
An object is placed 20cm from a concave mirror of focal length 10cm. The linear magnification of the image produced is?
Answer Details
The linear magnification of an image is given by the formula:
magnification = height of image / height of object = -v/u
where v is the image distance, u is the object distance, and the negative sign indicates that the image is inverted.
In this problem, the object is placed 20cm from a concave mirror of focal length 10cm. Since the object is placed beyond the focal point, the image will be real and inverted.
Using the mirror formula 1/f = 1/v + 1/u, we can find the image distance v:
1/10 = 1/v + 1/20
Solving for v, we get:
v = -20 cm
Now, we can use the magnification formula to find the linear magnification:
magnification = -v/u = -(-20)/20 = 1
Therefore, the linear magnification of the image produced is 1, which means the image is the same size as the object and is also inverted.
The answer is: 1.
Question 14 Report
In the diagram given the hanging mass m2 is adjusted until m1 is on the verge of sliding. The coefficient of static
Answer Details
I think the correct option is C (m2m1
). The coefficient of friction is a ratio of two forces and hence g will cancel out.
Question 15 Report
The resistance of a 40W car head lamp, drawing current from a 12V battery is ____.
Answer Details
The resistance of a 40W car headlamp can be calculated using Ohm's Law, which states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points, and inversely proportional to the resistance (R) of the conductor. The equation can be written as V = IR.
Since the power (P) of the headlamp is given as 40W and the voltage is 12V, we can calculate the current using the equation P = IV. Substituting I = P/V, we get I = 40/12 = 3.33A.
Finally, using Ohm's Law, we can calculate the resistance as R = V/I = 12/3.33 = 3.6Ω.
So, the resistance of the 40W car headlamp, drawing current from a 12V battery, is 3.6Ω.
Question 16 Report
Musical instruments playing the same note can be distinguished from one another owing to the difference in their
Answer Details
Different musical instruments playing the same note can be distinguished from one another due to the difference in their "timbre" or "tone color." Timbre refers to the unique character or quality of a sound that allows us to distinguish it from other sounds even when they have the same pitch and loudness. For example, a piano and a guitar playing the same note will sound different due to the differences in their timbre. This is why we can tell the difference between different instruments and why some instruments are better suited to certain styles of music than others.
Question 17 Report
Which of the following is an essential physical property of the wires uses for making fuses ?
Answer Details
The essential physical property of the wire used for making fuses is low melting point. This means that the wire should have a low temperature at which it melts and breaks, interrupting the flow of electrical current. This is important in a fuse because when there is an overload of electrical current, the wire will melt, breaking the circuit and preventing damage to the electrical system.
The other options, low density, low electrical resistivity, and hypothermal conductivity, are not as important for a fuse wire. Low density is the property of a material to be light, and it doesn't necessarily affect the performance of a fuse wire. Low electrical resistivity is the property of a material to have low resistance to the flow of electrical current, and it doesn't necessarily affect the performance of a fuse wire either. Hypothermal conductivity is the property of a material to conduct heat poorly, and it also doesn't necessarily affect the performance of a fuse wire.
Question 18 Report
A car traveled at a uniform speed of 100km/h, spends 15m moving from point A to point B along its route. The distance between A and B is
Answer Details
To calculate the distance between point A and point B, we can use the formula:
Distance = Speed x Time
where the speed is given as 100 km/h and the time is given as 15 minutes, which we need to convert to hours.
1 hour = 60 minutes, so 15 minutes = 15/60 hours = 0.25 hours.
Now, we can substitute these values into the formula:
Distance = 100 km/h x 0.25 h = 25 km
Therefore, the distance between point A and point B is 25 km.
is the correct answer.
Question 19 Report
A pulley system has three pulleys in the fixed block and two in the movable block and if the pulley has an efficiency of 72%, the mechanical advantage of the system is?
Answer Details
To make it easier understood
MA = E × Vr/100
Vr in a pulley system is the number of pulleys and in this case we have 5 (3 and 2)
So
MA = 72 × 5 = 360/100 = 3.6
Thanks
MA = E × Vr/100
Vr in a pulley system is the number of pulleys and in this case we have 5 (3 and 2)
So
MA = 72 × 5 = 360/100 = 3.6
Thanks
Question 20 Report
The friction which exist between two layers of liquid in relative motion is called
Answer Details
The correct answer is "Viscosity". Viscosity is the property of a fluid that describes its resistance to flow. When two layers of liquid are in relative motion, the viscosity of the liquid causes friction between the layers. This friction creates a resistance to the movement of one layer past the other. The greater the viscosity of the liquid, the greater the friction and the more difficult it is for the layers to move past each other. This property is important in many industrial and natural processes, such as the flow of oil in pipelines or the movement of blood through the human body.
Question 21 Report
What effort will a machine of efficiency 90% apply to a load of 180N if its efforts arm is twice as long as its load arm?
Answer Details
Question 22 Report
Which of the following obeys Ohm's law?
Answer Details
Ohm's law states that the current passing through a conductor is directly proportional to the voltage applied across it, given the temperature and other physical conditions remain constant.
Among the given options, only "all metals" obey Ohm's law. This is because metals have a linear relationship between their resistance and the applied voltage, meaning that the resistance of a metal remains constant regardless of the voltage applied. As a result, the current passing through a metal is directly proportional to the voltage applied, following Ohm's law.
On the other hand, a diode, all electrolytes, and glass do not obey Ohm's law. A diode is a semiconductor that has a non-linear current-voltage relationship, and its resistance is not constant. Similarly, electrolytes and glass are non-metallic substances that do not have a linear relationship between their resistance and the applied voltage. Their resistance can change significantly with the voltage applied, and hence they do not follow Ohm's law.
Question 23 Report
Which of the following does NOT describe the Image formed by a plane minor?
Answer Details
The option that does NOT describe the image formed by a plane mirror is "Magnified".
When an object is placed in front of a plane mirror, the image formed is:
1. Erect: The orientation of the object in the mirror is the same as the orientation of the object in real life. For example, if you raise your right hand in front of a plane mirror, the image in the mirror will also show your right hand raised.
2. Laterally inverted: The image formed in the mirror is flipped horizontally, which means that the left side of the object appears on the right side of the image and vice versa. For example, if you wear a shirt with the letter "H" on it and look at it in a plane mirror, the image will show the letter "H" flipped horizontally.
3. Same distance from the mirror as object: The image formed in the mirror is located behind the mirror at the same distance as the object is located in front of the mirror. For example, if you stand 1 meter away from a plane mirror, the image of yourself will also be located 1 meter away from the mirror, behind the mirror.
4. NOT magnified: The image formed in the plane mirror is of the same size as the object, which means that there is no magnification or reduction in the size of the image. For example, if you stand in front of a plane mirror with a height of 1 meter, the image of yourself in the mirror will also have a height of 1 meter.
Therefore, the correct answer is "Magnified", as the image formed by a plane mirror is not magnified.
Question 24 Report
Calculate the effective capacitance of the circuit in the diagram given
Answer Details
The three 2uf capacitors are in parallel to each other so u add them like this
2uf+2uf+2uf=6uf
So u have three capacitors in series
6uf 2uf and 3uf
They are in series so
1/C= 1/6+1/3=1/2
C=2uf
Then the same thing with the last two capay
1/2+1/2=1uf
Thanks
2uf+2uf+2uf=6uf
So u have three capacitors in series
6uf 2uf and 3uf
They are in series so
1/C= 1/6+1/3=1/2
C=2uf
Then the same thing with the last two capay
1/2+1/2=1uf
Thanks
Question 25 Report
Mercury which is spilled onto a glass surface forms ball-like shapes because____.
Answer Details
In case of small drops of mercury, the gravitational potential energy is negligible in comparison to the potential energy due to surface tension.Consequently, to keep the drop in equilibrium, the mercury drop’s surface tends to contract so that its surface area will be the least for a sphere and the drops will be spherical.
But in the case of bigger drops of mercury, the potential energy due to gravity is predominant over the potential energy due to surface tension.Consequently, to keep equilibrium , the mercury drop tends to assume minimum potential energy as possible, the drop becomes oval in shape and lower center of gravity.
But in the case of bigger drops of mercury, the potential energy due to gravity is predominant over the potential energy due to surface tension.Consequently, to keep equilibrium , the mercury drop tends to assume minimum potential energy as possible, the drop becomes oval in shape and lower center of gravity.
Question 26 Report
What type of reaction is represented by the following scheme?
\( {}_{1}^{2}X + {}_{1}^{2}Y \longrightarrow {}_{2}^{3}Z + {}_{1}^{0}n + \text{energy} \)
Answer Details
The type of reaction represented by the given scheme is a nuclear fission reaction.
Nuclear fission is a process where a heavy nucleus is split into smaller nuclei with the release of energy. In the given scheme, a heavy element X is split into two lighter elements, Y and Z, along with the release of energy and some neutrons (n).
In a nuclear fission reaction, a neutron is usually absorbed by the nucleus of the heavy element, which then becomes unstable and splits into two smaller nuclei and some neutrons. These neutrons can then go on to split other heavy nuclei, resulting in a chain reaction.
In the given scheme, the release of energy and the presence of neutrons suggest that it is a fission reaction. Moreover, the scheme depicts the process of splitting a heavy element into two lighter elements, which is a characteristic of a fission reaction.
Therefore, the type of reaction represented by the given scheme is a nuclear fission reaction.
Question 27 Report
The linear expansivity of brass is \(2 \times 10^{-5}\,\text{C}^{-1}\). If the volume of a piece of brass is 15.00cm at 0°C, what is the volume at 100°C
Answer Details
The linear expansivity of brass is given as 2 x 10^-5 /°C. This means that for every 1°C increase in temperature, the brass expands by 2 x 10^-5 of its original size.
To find the new volume of the brass at 100°C, we need to take into account the expansion in all three dimensions (length, width, and height). Since the expansivity given is for length only, we need to find the expansivity in all three dimensions by multiplying it by 3.
The expansivity in all three dimensions is:
3 x (2 x 10^-5 /°C) = 6 x 10^-5 /°C
To find the new volume, we can use the formula:
Vf = Vi (1 + αΔT)
where Vf is the final volume, Vi is the initial volume, α is the expansivity in all three dimensions, and ΔT is the change in temperature.
Plugging in the values, we get:
Vf = 15.00 cm3 (1 + (6 x 10^-5 /°C) x (100°C - 0°C))
Vf = 15.09 cm3
Therefore, the volume of the brass at 100°C is 15.09 cm3.
Question 28 Report
A man hears his echo from a nearby hill 2s after he shouted. If the frequency of his voice is 260Hz and the wavelength is 1.29m, how far away is the hill
Answer Details
The speed of sound in air is approximately 343 meters per second at room temperature. The formula for the speed of sound is:
Speed of sound = Frequency × Wavelength
In this problem, we are given the frequency (260 Hz) and the wavelength (1.29 m) of the sound wave. We can use these values to calculate the speed of sound:
Speed of sound = 260 Hz × 1.29 m = 335.4 m/s
Next, we need to use the fact that the man hears his echo 2 seconds after he shouted. Since the sound wave traveled from the man to the hill and then back to the man, the total distance traveled by the sound wave is twice the distance from the man to the hill. We can use the formula:
Distance = Speed × Time
to calculate the distance from the man to the hill:
Distance = (335.4 m/s) × (2 s/2) = 335.4 m
Therefore, the hill is 335.4 meters away from the man. The answer is option (B), 335.4m.
Question 29 Report
Which of the following diagrams represents correctly an n-p-n transistor?
i.
ii
iii
Answer Details
Question 30 Report
A 20kg mass is to be pulled up a slope inclined at 300 to the horizontal. If efficiency of the plane is 75%. The force required to pull the load up the plane is J [g=10ms\(^{-2}\)]
Answer Details
The force required to pull a 20kg mass up a slope inclined at 300 can be calculated using the formula:
force = mass * gravity * sin(angle)
where mass is 20kg, gravity is 10 m/s^2 and angle is 300.
The formula for efficiency is:
efficiency = output force / input force
where output force is the force required to pull the mass up the slope and input force is the force applied to the rope.
Since the efficiency of the plane is 75%, the input force is 4 times the output force.
So, the output force can be calculated as:
output force = input force / 4
input force = mass * gravity * sin(angle) / efficiency
input force = 20 * 10 * sin(300) / 0.75
input force = 533.2 N
And the output force can be calculated as:
output force = input force / 4
output force = 533.2 / 4
output force = 133.3 N
So, the force required to pull the load up the plane is 133.3 N.
Question 31 Report
The amount of heat needed to raise the temperature of 10kg of Copper by 1K is its
Answer Details
The correct answer is "specific heat capacity."
Specific heat capacity is a measure of how much heat energy is required to raise the temperature of a certain amount of a substance by 1 degree Celsius (or 1 Kelvin, which is the same size as 1 degree Celsius).
In this case, we are dealing with 10kg of copper, so we need to know the specific heat capacity of copper. The specific heat capacity of copper is 0.385 J/g°C (joules per gram per degree Celsius).
To calculate the amount of heat needed to raise the temperature of 10kg of copper by 1K, we need to know the total mass of copper (10kg) and the specific heat capacity of copper (0.385 J/g°C).
The formula for calculating the amount of heat energy required is:
Heat energy = mass x specific heat capacity x change in temperature
Since we want to raise the temperature by 1K, the change in temperature is 1K.
So, the amount of heat energy required to raise the temperature of 10kg of copper by 1K is:
Heat energy = 10kg x 0.385 J/g°C x 1K = 3.85 kJ
Therefore, it takes 3.85 kilojoules (kJ) of heat energy to raise the temperature of 10kg of copper by 1K.
Question 32 Report
Which of the following may be used to explain a mirage?
I. Layers of air near the road surface have varying refractive indices in hot weather
II. Road surfaces sometimes become good reflectors in hot weather
III. Light from the sky can be reflected upwards after coming close to the road surface.
Answer Details
The phenomenon of a mirage can be explained by options I and III. A mirage is an optical illusion that occurs when light rays passing through a medium with varying refractive indices create a false image of distant objects or even the sky. In hot weather, the air near the road surface becomes hotter and less dense than the air above, causing the light passing through it to bend and create a reflection of the sky or objects in the distance. This effect is known as a temperature inversion. Additionally, light from the sky can be reflected upwards after coming close to the road surface, adding to the illusion of a reflected object or the sky. Option II, which suggests that road surfaces become good reflectors in hot weather, is not a valid explanation for a mirage. Therefore, the correct answer is: I and III only.
Question 33 Report
Palm oil from a bottle flows out more easily after it has been heated because the
Answer Details
Molecules cannot be given energy during the heating and the molecules of oil cannot force each other out
Question 34 Report
The electrochemical equivalent of silver is 0.0012g/C. If 36.0g of silver is to be deposited by electrolysis on a surface by passing a steady current for 5mins, the current must be?
Answer Details
The electrochemical equivalent of silver is a measure of the amount of silver that is deposited on a surface per unit of charge. In this case, the electrochemical equivalent of silver is 0.0012 grams per Coulomb of charge. To deposit 36.0 grams of silver by electrolysis, we need to know the amount of charge that must be passed through the solution.
The amount of charge is given by:
Q = m/z
where m is the mass of silver to be deposited, 0.0012 is the electrochemical equivalent of silver, and z is the charge on one mole of electrons (z = 1 for a single electron).
So, the amount of charge required is:
Q = 36.0 g / 0.0012 g/C = 30000 C
The current, I, is given by:
I = Q / t
where t is the time for which the current is flowing. In this case, t = 5 minutes.
So, the current required is:
I = 30000 C / (5 x 60 s) = 100 A
Therefore, the current must be 100 Amperes.
Question 35 Report
The critical angle for light travelling from a transparent medium to air s measured as 340. The refractive index of the medium is
Answer Details
The critical angle is the angle of incidence at which light is just able to pass through the interface between two media and not reflect back. When light travels from a medium with a higher refractive index to a medium with a lower refractive index, it slows down and bends towards the normal. If the angle of incidence is increased, the light will eventually reach a point where it will not be able to escape the higher index medium and will be totally reflected back. This is the critical angle.
The formula for the critical angle can be expressed as follows:
sin(θc) = n2/n1
Where θc is the critical angle, n1 is the refractive index of the first medium, and n2 is the refractive index of the second medium. In this case, the first medium is the transparent medium and the second medium is air, which has a refractive index of approximately 1.
By substituting the value of sin(θc) with the value of 340, and n2 with 1, we can solve for n1.
sin(340) = n1/1
n1 = 1/sin(340)
The value of n1 calculated using this formula is approximately 1.79, which means that the refractive index of the transparent medium is 1.79.
Question 36 Report
Which of the following phenomena cannot be explained by the molecular theory of matter?
Answer Details
Conduction: the flow of internal energy from a region of higher temperature to lower temperature
Convection: heat transfer due to bulk movement of molecules within fluids
Expansion: the action of becoming larger or more extensive
Convection: heat transfer due to bulk movement of molecules within fluids
Expansion: the action of becoming larger or more extensive
Question 37 Report
A room is heated by means of a charcoal fire, an occupants of the room standing away from the fire is warmed mainly by
Answer Details
The main way that the occupants of a room standing away from a charcoal fire are warmed is by radiation. Radiation is the transfer of heat energy through electromagnetic waves, and it can travel through empty space.
In this scenario, the charcoal fire emits radiation in the form of infrared waves, which travel through the air and warm up the objects (including the occupants) in the room. Convection, on the other hand, is the transfer of heat through the movement of fluids (such as air), but in this case, the air in the room is not being actively circulated by a fan or other mechanism. Conduction involves the transfer of heat through direct contact between two objects, but the occupants are not in direct contact with the fire. Reflection refers to the bouncing of radiation off a surface, but it is not a significant factor in this scenario as most of the radiation is absorbed by the objects in the room.
Question 38 Report
An object weighs 30N in air and 21N in water. The weight of the object when completely immersed in a liquid of relative density 1.4 is
Answer Details
Weight of water displaced = upthrust = 30 - 21 = 9N
Mass of water displaced = 910
= 0.9kg
Volume of object = 9 × 10−4
m3
= (9 × 10−4
) (1.4 ×103)
= 1.26kg = 12N
30 - 12.6 = 17.4N
Question 39 Report
The inner diameter of a small test tube can be measured accurately using a
Answer Details
A vernier caliper is a measuring device used to precisely measure linear dimensions. It is a very useful tool to use when measuring the diameter of a round objects like cylinders because the measuring jaws can be secured on either side of the circumference.
Vernier calipers have both a fixed main scale and a moving vernier scale. The main scale is graduated in either millimetres or tenths of an inch. The vernier scale allows much more precise readings to be taken (usually to the nearest 0.02mm or 0.001 inch) in comparison to a standard ruler (which only measures to th nearest 1mm or 0.25 inch).
The vernier scale was invented by French mathematician Pierre Vernier in 1631. As part of the vernier caliper, it is used together with the main scale, and helps to provide very precise measurements. Vernier calipers usually show either imperial or metric measurements, but some measure in both.
Vernier calipers have both a fixed main scale and a moving vernier scale. The main scale is graduated in either millimetres or tenths of an inch. The vernier scale allows much more precise readings to be taken (usually to the nearest 0.02mm or 0.001 inch) in comparison to a standard ruler (which only measures to th nearest 1mm or 0.25 inch).
The vernier scale was invented by French mathematician Pierre Vernier in 1631. As part of the vernier caliper, it is used together with the main scale, and helps to provide very precise measurements. Vernier calipers usually show either imperial or metric measurements, but some measure in both.
Question 40 Report
The pitch of an acoustic device can be increased by
Answer Details
The pitch of an acoustic device refers to the perceived highness or lowness of a sound, and is determined by the frequency of the sound wave. To increase the pitch of an acoustic device, you need to increase the frequency of the sound wave. This can be done by increasing the number of vibrations per second that the device produces.
So, the correct answer is to "increase the frequency".
