Physics Syllabus (JEE Main)
Q. In a potentiometer setup, if the wire has a resistance of 10 ohms and a current of 0.5 A flows through it, what is the potential drop across the wire?
A.
2.5 V
B.
5 V
C.
10 V
D.
15 V
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Solution
The potential drop is calculated using Ohm's law: V = IR = 0.5 A * 10 ohms = 5 V.
Correct Answer: B — 5 V
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Q. In a potentiometer setup, if the wire is made of a material with higher resistivity, what will be the effect on the measurement?
A.
Measurements will be more accurate
B.
Measurements will be less accurate
C.
There will be no effect
D.
It will not work
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Solution
Higher resistivity increases the resistance of the wire, which can lead to a larger voltage drop along the wire, potentially affecting the accuracy of the measurements.
Correct Answer: B — Measurements will be less accurate
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Q. In a potentiometer setup, if the wire is made of a material with higher resistivity, what will be the effect on the potential gradient?
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
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Solution
Higher resistivity increases the resistance of the wire, which can decrease the potential gradient for a given voltage.
Correct Answer: B — It decreases
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Q. In a potentiometer setup, if the wire is made of a material with higher resistivity, what effect does it have on the potential gradient?
A.
It increases
B.
It decreases
C.
It remains unchanged
D.
It becomes infinite
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Solution
Higher resistivity increases the resistance of the wire, which can lead to a decrease in current and thus affect the potential gradient.
Correct Answer: B — It decreases
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Q. In a potentiometer setup, what is the effect of increasing the length of the wire on the accuracy of voltage measurement?
A.
Increases accuracy
B.
Decreases accuracy
C.
No effect on accuracy
D.
Depends on the voltage
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Solution
Increasing the length of the wire increases the accuracy of voltage measurement due to a smaller potential gradient.
Correct Answer: A — Increases accuracy
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Q. In a potentiometer setup, what is the role of the jockey?
A.
To measure current
B.
To connect the circuit
C.
To find the null point
D.
To provide a constant voltage
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Solution
The jockey is used to touch the wire and find the null point where the galvanometer shows zero deflection, indicating balance.
Correct Answer: C — To find the null point
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Q. In a potentiometer, if the length of the wire is 20 m and the potential difference is 10 V, what is the voltage drop per meter?
A.
0.5 V/m
B.
1 V/m
C.
2 V/m
D.
5 V/m
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Solution
The voltage drop per meter is calculated as V/L = 10 V / 20 m = 0.5 V/m.
Correct Answer: B — 1 V/m
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Q. In a potentiometer, if the wire has a uniform cross-section, how does it affect the potential gradient?
A.
It becomes non-uniform
B.
It remains uniform
C.
It increases
D.
It decreases
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Solution
If the wire has a uniform cross-section, the potential gradient remains uniform along its length.
Correct Answer: B — It remains uniform
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Q. In a potentiometer, if the wire is made of a material with higher resistivity, what effect does it have on the potential gradient?
A.
It increases the potential gradient.
B.
It decreases the potential gradient.
C.
It has no effect.
D.
It makes the potentiometer unusable.
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Solution
Higher resistivity increases the resistance of the wire, which decreases the current for a given voltage, thus increasing the potential gradient.
Correct Answer: B — It decreases the potential gradient.
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Q. In a potentiometer, what is the role of the jockey?
A.
To measure current.
B.
To connect the circuit.
C.
To find the balance point.
D.
To provide a reference voltage.
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Solution
The jockey is used to find the balance point where the potential difference is equal to the reference voltage.
Correct Answer: C — To find the balance point.
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Q. In a practical Wheatstone bridge, what is the effect of temperature on resistance measurements?
A.
Temperature has no effect
B.
Resistance increases with temperature
C.
Resistance decreases with temperature
D.
It depends on the material
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Solution
The effect of temperature on resistance measurements in a Wheatstone bridge depends on the material of the resistors, as different materials have different temperature coefficients.
Correct Answer: D — It depends on the material
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Q. In a practical Wheatstone bridge, what is the effect of temperature on the resistances?
A.
Resistances remain constant
B.
Resistances increase with temperature
C.
Resistances decrease with temperature
D.
Temperature has no effect
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Solution
In general, the resistance of conductors increases with temperature due to increased atomic vibrations.
Correct Answer: B — Resistances increase with temperature
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Q. In a practical Wheatstone bridge, what is the effect of temperature on the resistors?
A.
It has no effect
B.
It can change resistance values
C.
It only affects the galvanometer
D.
It only affects the power supply
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Solution
Temperature changes can affect the resistance values of the resistors, thus affecting the balance condition.
Correct Answer: B — It can change resistance values
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Q. In a practical Wheatstone bridge, what is the main source of error?
A.
Temperature variations
B.
Resistance of the connecting wires
C.
Calibration of the galvanometer
D.
Non-ideal resistors
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Solution
Non-ideal resistors can introduce errors in the measurements due to their tolerance and temperature coefficients.
Correct Answer: D — Non-ideal resistors
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Q. In a prism, if the angle of incidence is equal to the angle of emergence, what can be said about the angle of deviation?
A.
It is zero
B.
It is equal to the angle of incidence
C.
It is equal to the angle of emergence
D.
It is equal to the angle of the prism
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Solution
When the angle of incidence equals the angle of emergence, the angle of deviation is equal to the angle of the prism.
Correct Answer: D — It is equal to the angle of the prism
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Q. In a prism, if the angle of the prism is 60 degrees, what is the minimum angle of deviation for light passing through it?
A.
30 degrees
B.
60 degrees
C.
90 degrees
D.
45 degrees
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Solution
The minimum angle of deviation (D) for a prism is given by D = A, where A is the angle of the prism. Therefore, for a 60-degree prism, the minimum angle of deviation is 30 degrees.
Correct Answer: A — 30 degrees
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Q. In a process where 100 J of heat is added to a system and the internal energy increases by 40 J, how much work is done by the system?
A.
60 J
B.
40 J
C.
100 J
D.
140 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W, we have 40 J = 100 J - W, thus W = 100 J - 40 J = 60 J.
Correct Answer: A — 60 J
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Q. In a process where 300 J of heat is added to a system and the internal energy increases by 100 J, how much work is done by the system?
A.
200 J
B.
100 J
C.
300 J
D.
400 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W. Rearranging gives W = Q - ΔU. Here, W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. In a process where 300 J of heat is added to a system and the system does 100 J of work, what is the change in internal energy?
A.
200 J
B.
100 J
C.
300 J
D.
400 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. In a process where 300 J of heat is added to a system and the system does 100 J of work, what is the internal energy change?
A.
200 J
B.
300 J
C.
100 J
D.
400 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. In a refrigerator, the work done on the system is used to:
A.
Increase the internal energy
B.
Decrease the internal energy
C.
Transfer heat from cold to hot
D.
Transfer heat from hot to cold
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Solution
In a refrigerator, work is done on the system to transfer heat from a colder body to a hotter body, which is against the natural flow of heat.
Correct Answer: C — Transfer heat from cold to hot
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Q. In a region of space where the electric field is uniform, what is the electric flux through a surface area A oriented perpendicular to the field?
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Solution
The electric flux Φ through a surface area A in a uniform electric field E is given by Φ = EA when the surface is perpendicular to the field.
Correct Answer: A — EA
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Q. In a region where the electric field is uniform, how does the electric flux through a surface depend on the angle between the field and the normal to the surface?
A.
It is maximum when the angle is 0°
B.
It is maximum when the angle is 90°
C.
It is independent of the angle
D.
It is zero when the angle is 0°
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Solution
The electric flux is maximum when the angle between the electric field and the normal to the surface is 0°, as Φ = E·A·cos(θ).
Correct Answer: A — It is maximum when the angle is 0°
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Q. In a region where the electric field is uniform, what is the shape of the Gaussian surface that would yield the simplest calculation of electric flux?
A.
Sphere
B.
Cube
C.
Cylinder
D.
Plane
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Solution
A plane is the simplest Gaussian surface for uniform electric fields, as it allows for straightforward calculation of flux.
Correct Answer: D — Plane
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Q. In a rotating system, if the angular momentum is doubled while the moment of inertia remains constant, what happens to the angular velocity?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
Since L = Iω, if L is doubled and I remains constant, then ω must also double.
Correct Answer: A — It doubles
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Q. In a seesaw, if one child exerts a force of 30 N at a distance of 1.5 m from the pivot, what is the torque produced by this child?
A.
15 Nm
B.
30 Nm
C.
45 Nm
D.
60 Nm
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Solution
Torque (τ) = F × r = 30 N × 1.5 m = 45 Nm.
Correct Answer: C — 45 Nm
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Q. In a seesaw, if one child exerts a force of 30 N at a distance of 2 m from the pivot, what is the torque exerted by that child?
A.
15 Nm
B.
30 Nm
C.
60 Nm
D.
0 Nm
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Solution
Torque (τ) = F × r = 30 N × 2 m = 60 Nm.
Correct Answer: C — 60 Nm
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Q. In a seesaw, if one child exerts a torque of 30 N·m on one side, what torque must the other child exert to balance it?
A.
15 N·m
B.
30 N·m
C.
45 N·m
D.
60 N·m
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Solution
To balance the seesaw, the other child must exert an equal torque of 30 N·m.
Correct Answer: B — 30 N·m
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Q. In a semiconductor, what is the term for the energy required to move an electron from the valence band to the conduction band?
A.
Ionization energy
B.
Band gap energy
C.
Thermal energy
D.
Activation energy
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Solution
The energy required to move an electron from the valence band to the conduction band is known as the band gap energy.
Correct Answer: B — Band gap energy
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Q. In a series circuit with a 12V battery and three resistors of 2Ω, 3Ω, and 5Ω, what is the current flowing through the circuit?
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Solution
Total resistance R = 2Ω + 3Ω + 5Ω = 10Ω. Current I = V / R = 12V / 10Ω = 1.2A.
Correct Answer: B — 2A
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