Physics Test 220

Question 1
4 / -1

In a series LCR circuit, R = 200Ω and the voltage and frequency of the main supply are 220 V and 50 Hz, respectively. On taking out the capacitance from the circuit, the current lags behind the voltage by 30°. On taking out the inductor from the circuit, the current leads the voltage by 30°. The power dissipated in the LCR circuit is

A
242 W

B
305 W

C
210 W

D
0 W

Question 2
4 / -1

Two equally charged identical metal spheres A and B repel each other with a force of 2.0 ×10^–5 N. Another identical uncharged sphere C is made to touch A and then placed at the midpoint between A and B. What is the net force on C?

A
6 × 10^-6 N along BC

B
5 × 10^-4 N along BC

C
2 × 10^-5 N along BC

D
3 × 10^-2 N along BC

Question 3
4 / -1

What is the use of ball bearings between hubs and the axle of ceiling fans and bicycles?

A
Converts rolling friction into sliding friction

B
Converts static friction into kinetic friction

C
Converts sliding friction into rolling friction

D
Converts static friction into rolling friction

Question 4
4 / -1

A particle of mass 0.3 kg is subjected to a force F = -kx, with k = 15 N/m. What will be its initial acceleration if it is released from a point 20 cm away from the origin?

A
5 m/s²

B
10 m/s²

C
3 m/s²

D
15 m/s²

Question 5
4 / -1

A projectile is fired at an angle 60° with some velocity u. If the angle is changed infinitesimally, let the corresponding fractional changes in the range and the time of flight be x and y, respectively, then find the value of y.

A

B

C
-2x

D
2x

Question 6
4 / -1

The velocity of a particle is v = v₀ + gt + ft². If its position is x = 0 at t = 0, then its displacement after unit time (t = 1) is

A
v₀ + g/2 + f

B
v₀ + 2g + 3f

C
v₀ + g/2 + f/3

D
v₀ + g + f

Question 7
4 / -1

A giant telescope in an observatory has an objective of focal length 19 m and an eye-piece of focal length 1.0 cm. In normal adjustment, the telescope is used to view the moon. What is the diameter of the image of the moon formed by the objective? (The diameter of the moon is 3.5 × 10⁶ m and the radius of the lunar orbit around the Earth is 3.8 × 10⁸ m)

A
10 cm

B
12.5 cm

C
15 cm

D
17.5 cm

Question 8
4 / -1

Carbon, silicon and germanium have four valence electrons each. At room temperature, which of the following statements is the most appropriate?

A
The number of free electrons for conduction is significant only in Si and Ge, but small in C.

B
The number of free conduction electrons is significant in C, but small in Si ad Ge.

C
The number of free conduction electrons is negligibly small in all three.

D
The number of free electrons for conduction is significant in all three.

Question 9
4 / -1

A metallic container is completely filled with a liquid. The coefficient of linear expansion of the metal is 2.0 × 10^-6per °C and the coefficient of cubical expansion of the liquid is 6.0 × 10^-6 per °C. On heating the vessel,

A
the liquid will overflow

B
the level of the liquid will fall

C
the level of the liquid will remain unchanged

D
the level of liquid will rise or fall depending on the nature of the metal and of the liquid

Question 10
4 / -1

Directions: In this question, two statements are given, numbered 1 and 2. Read both the statements carefully and choose the correct option accordingly.

Statement-1: The temperature dependence of resistance is usually given as R = R₀(1 + αΔt). The resistance of a wire changes from 100 Ω to 150 Ω when its temperature is increased from 27°C to 227°C. This implies that α = 2.7 10^-3/°C.

Statement-2: R = R₀(1 + αΔt) is valid only when the change in the temperature ΔT is small and ΔR = (R - R₀) << R₀.

A
Statement-1 is true, but statement-2 is false.

B
Both statements 1 and 2 are true, and statement-2 is the correct explanation for statement-1.

C
Both statements 1 and 2 are true, but statement-2 is not the correct explanation for statement-1.

D
Statement-1 is false, but statement-2 is true.

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Physics Test 22...

Question 1

242 W

305 W

210 W

0 W

Question 2

6 × 10-6 N along BC

5 × 10-4 N along BC

2 × 10-5 N along BC

3 × 10-2 N along BC

Question 3

Converts rolling friction into sliding friction

Converts static friction into kinetic friction

Converts sliding friction into rolling friction

Converts static friction into rolling friction

Question 4

5 m/s2

10 m/s2

3 m/s2

15 m/s2

Question 5

-2x

2x

Question 6

v0 + g/2 + f

v0 + 2g + 3f

v0 + g/2 + f/3

v0 + g + f

Question 7

10 cm

12.5 cm

15 cm

17.5 cm

Question 8

The number of free electrons for conduction is significant only in Si and Ge, but small in C.

The number of free conduction electrons is significant in C, but small in Si ad Ge.

The number of free conduction electrons is negligibly small in all three.

The number of free electrons for conduction is significant in all three.

Question 9

the liquid will overflow

the level of the liquid will fall

the level of the liquid will remain unchanged

the level of liquid will rise or fall depending on the nature of the metal and of the liquid

Question 10

Statement-1 is true, but statement-2 is false.

Both statements 1 and 2 are true, and statement-2 is the correct explanation for statement-1.

Both statements 1 and 2 are true, but statement-2 is not the correct explanation for statement-1.

Statement-1 is false, but statement-2 is true.

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Question Analysis

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6 × 10^-6 N along BC

5 × 10^-4 N along BC

2 × 10^-5 N along BC

3 × 10^-2 N along BC

5 m/s²

10 m/s²

3 m/s²

15 m/s²

v₀ + g/2 + f

v₀ + 2g + 3f

v₀ + g/2 + f/3

v₀ + g + f