Physics Syllabus (JEE Main)
Q. If the angle between the transmission axis of two polarizers is 90 degrees, what is the intensity of light passing through them?
A.
Maximum intensity
B.
Half of the original intensity
C.
Zero intensity
D.
Equal to the intensity of the first polarizer
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Solution
When the angle between the transmission axes of two polarizers is 90 degrees, no light passes through, resulting in zero intensity.
Correct Answer: C — Zero intensity
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Q. If the angle of incidence in a medium is 45° and the refractive index of the medium is 1.5, what is the angle of refraction in air?
A.
30°
B.
45°
C.
60°
D.
90°
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Solution
Using Snell's law: n1 * sin(θ1) = n2 * sin(θ2), 1.5 * sin(45°) = 1 * sin(θ2) => sin(θ2) = 1.5 * 0.7071 = 1.0607, which is not possible, hence total internal reflection occurs.
Correct Answer: C — 60°
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Q. If the angle of incidence in a medium is 70° and the refractive index of the medium is 1.5, will total internal reflection occur?
A.
Yes
B.
No
C.
Only at certain angles
D.
Not applicable
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Solution
Since 70° > θc = sin⁻¹(1/1.5) ≈ 41.8°, total internal reflection will occur.
Correct Answer: A — Yes
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Q. If the angle of incidence in glass (n=1.5) is 60°, will total internal reflection occur when light travels to air?
A.
Yes
B.
No
C.
Depends on the angle
D.
Not enough information
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Solution
Since the critical angle for glass to air is sin⁻¹(1.00/1.5) ≈ 41.8°, and 60° > 41.8°, total internal reflection occurs.
Correct Answer: A — Yes
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Q. If the angle of incidence is 30° in a medium with a refractive index of 1.5, what is the angle of refraction in air?
A.
19.5°
B.
20.0°
C.
22.5°
D.
25.0°
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Solution
Using Snell's law: n1 * sin(θ1) = n2 * sin(θ2). Here, n1 = 1.5, n2 = 1.0, and θ1 = 30°. Thus, sin(θ2) = (1.5 * sin(30°))/1.0 = 0.75, leading to θ2 ≈ 48.6°.
Correct Answer: A — 19.5°
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Q. If the angle of incidence is 70° in a medium with a refractive index of 1.5, what is the angle of refraction in air?
A.
30°
B.
20°
C.
10°
D.
Total internal reflection occurs
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Solution
Since the angle of incidence (70°) is greater than the critical angle (approximately 41.8° for glass to air), total internal reflection occurs.
Correct Answer: D — Total internal reflection occurs
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Q. If the angle of incidence is 70° in a medium with a refractive index of 1.6, will total internal reflection occur when it hits air?
A.
Yes
B.
No
C.
Only if the angle is less than 90°
D.
Not enough information
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Solution
Critical angle θc = sin⁻¹(1/1.6) ≈ 38.7°. Since 70° > 38.7°, total internal reflection occurs.
Correct Answer: A — Yes
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Q. If the angle of incidence is 70° in glass (n=1.5), will total internal reflection occur when light travels to air?
A.
Yes
B.
No
C.
Only if the angle of refraction is 30°
D.
Only if the angle of refraction is 45°
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Solution
The critical angle for glass to air is sin⁻¹(1/1.5) ≈ 41.8°. Since 70° > 41.8°, total internal reflection will occur.
Correct Answer: A — Yes
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Q. If the angle of incidence is equal to the angle of refraction, what can be said about the two media?
A.
They are the same medium.
B.
They have the same refractive index.
C.
The light is traveling in a vacuum.
D.
The light is not refracted.
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Solution
When the angle of incidence equals the angle of refraction, it indicates that the light is passing from one medium to another of the same optical density, hence they are the same medium.
Correct Answer: A — They are the same medium.
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Q. If the angle of incidence is equal to the angle of refraction, what is the medium?
A.
Vacuum
B.
Air
C.
Glass
D.
Optically denser medium
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Solution
According to Snell's law, if the angle of incidence equals the angle of refraction, the light is traveling in the same medium, which can be vacuum or air.
Correct Answer: A — Vacuum
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Q. If the angle of incidence is equal to the critical angle, what is the angle of refraction?
A.
0°
B.
45°
C.
90°
D.
It cannot be determined.
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Solution
At the critical angle, the angle of refraction is 90°, meaning the refracted ray travels along the boundary.
Correct Answer: C — 90°
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Q. If the angle of incidence is equal to the critical angle, what is the behavior of the light ray?
A.
It is refracted at 90°.
B.
It is totally internally reflected.
C.
It is absorbed.
D.
It is transmitted.
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Solution
When the angle of incidence equals the critical angle, the light ray is refracted along the boundary at 90°, marking the threshold for total internal reflection.
Correct Answer: A — It is refracted at 90°.
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Q. If the angle of inclination of a plane increases, what happens to the static frictional force acting on an object resting on the plane?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Becomes zero
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Solution
As the angle increases, the component of gravitational force parallel to the plane increases, which can lead to a decrease in static friction until it reaches its maximum value.
Correct Answer: B — Decreases
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Q. If the angle of inclination of a plane increases, what happens to the static friction force acting on an object resting on the plane?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Becomes zero
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Solution
As the angle increases, the component of gravitational force parallel to the plane increases, which can lead to a decrease in static friction until it reaches its maximum value.
Correct Answer: B — Decreases
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Q. If the angular frequency of a simple harmonic motion is 5 rad/s, what is the time period?
A.
0.2 s
B.
0.4 s
C.
1.25 s
D.
2 s
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Solution
The time period T is given by T = 2π/ω. Therefore, T = 2π/5 = 0.4 s.
Correct Answer: A — 0.2 s
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Q. If the angular momentum of a rotating body is doubled while its moment of inertia remains constant, what happens to its angular velocity?
A.
Doubles
B.
Halves
C.
Remains the same
D.
Quadruples
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Solution
L = Iω; if L is doubled and I is constant, then ω must also double.
Correct Answer: A — Doubles
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Q. If the angular momentum of a rotating object is conserved, what can be said about its moment of inertia and angular velocity?
A.
Both increase
B.
Both decrease
C.
One increases and the other decreases
D.
Remain constant
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Solution
If angular momentum is conserved, an increase in moment of inertia results in a decrease in angular velocity, and vice versa.
Correct Answer: C — One increases and the other decreases
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Q. If the angular momentum of a rotating object is doubled while its moment of inertia remains constant, what happens to its angular velocity?
A.
Doubles
B.
Halves
C.
Remains the same
D.
Increases by a factor of 4
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Solution
Angular momentum L = Iω; if L is doubled and I remains constant, ω must also double.
Correct Answer: A — Doubles
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Q. If the angular momentum of a system is conserved, which of the following statements is true?
A.
Net external torque is zero
B.
Net external force is zero
C.
Kinetic energy is conserved
D.
Linear momentum is conserved
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Solution
Angular momentum is conserved when the net external torque acting on the system is zero.
Correct Answer: A — Net external torque is zero
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Q. If the angular momentum of a system is zero, what can be said about the motion of the system?
A.
It is at rest
B.
It is moving linearly
C.
It is rotating
D.
It can be in any motion
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Solution
Zero angular momentum does not imply rest; it can be in linear motion.
Correct Answer: D — It can be in any motion
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Q. If the angular momentum of a system is zero, what can be said about the motion of the particles in the system?
A.
They are at rest
B.
They are moving in a straight line
C.
They are rotating
D.
They are in circular motion
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Solution
Zero angular momentum implies no net rotation; particles can still move linearly.
Correct Answer: B — They are moving in a straight line
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Q. If the angular velocity of a rotating object is doubled, what happens to its centripetal acceleration?
A.
It remains the same
B.
It doubles
C.
It quadruples
D.
It halves
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Solution
Centripetal acceleration (a_c) = ω²r. If ω is doubled, a_c becomes (2ω)²r = 4ω²r.
Correct Answer: C — It quadruples
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Q. If the area of a loop in a magnetic field is doubled while keeping the magnetic field strength constant, what happens to the magnetic flux?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
Magnetic flux (Φ) is given by Φ = B * A. If the area (A) is doubled, the magnetic flux also doubles.
Correct Answer: A — It doubles
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Q. If the area of a loop is doubled while keeping the magnetic field constant, how does the magnetic flux change?
A.
It remains the same
B.
It doubles
C.
It triples
D.
It halves
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Solution
Magnetic flux Φ is given by Φ = B * A. If the area A is doubled while B remains constant, the magnetic flux also doubles.
Correct Answer: B — It doubles
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Q. If the area of a loop is doubled while the magnetic field remains constant, how does the induced EMF change?
A.
Doubles
B.
Halves
C.
Remains the same
D.
Quadruples
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Solution
Induced EMF is proportional to the area of the loop. If the area is doubled, the induced EMF also doubles.
Correct Answer: A — Doubles
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Q. If the area of a rectangle is calculated as 30 m² with an uncertainty of ±0.5 m², what is the relative error in the area measurement?
A.
0.0167
B.
0.017
C.
0.015
D.
0.02
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Solution
Relative error = (absolute error / measured value) = 0.5 / 30 = 0.0167.
Correct Answer: A — 0.0167
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Q. If the area of a rectangle is calculated as 50 m² with a length of 10 m and an uncertainty of ±0.1 m in length, what is the uncertainty in the area?
A.
1 m²
B.
0.5 m²
C.
0.2 m²
D.
0.1 m²
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Solution
Uncertainty in area = 2 * length * uncertainty in length = 2 * 10 * 0.1 = 2 m².
Correct Answer: B — 0.5 m²
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Q. If the balance length of a potentiometer is 50cm for a cell of unknown emf, and the potential gradient is 4 V/m, what is the emf of the cell?
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Solution
The emf is calculated as V = potential gradient × length = 4 V/m × 0.5 m = 2 V.
Correct Answer: B — 4V
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Q. If the balancing length of a potentiometer is found to be 40 cm for a cell of emf 2V, what is the potential gradient if the total length of the wire is 100 cm?
A.
5 V/m
B.
2 V/m
C.
4 V/m
D.
3 V/m
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Solution
The potential gradient is V/L = 2V/0.4m = 5 V/m.
Correct Answer: A — 5 V/m
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Q. If the charge density of a non-conducting sphere increases linearly with radius, how does the electric field vary inside the sphere?
A.
Linearly with radius
B.
Quadratically with radius
C.
Constant
D.
Inversely with radius
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Solution
The electric field inside a non-conducting sphere with linearly increasing charge density varies linearly with radius.
Correct Answer: A — Linearly with radius
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