Physics Test 144

Result

Physics Test 144

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Question 1
4 / -1

Frequency of tuning fork A is 256 Hz. It produces four beats/second with tuning fork B. When wax is applied at tuning fork B then 6 beats/second are heard. By reducing little amount of wax 4 beats/second are heard. Frequency of B is :

A
250 Hz

B
260 Hz

C
252 Hz

D
256 Hz
Question 2
4 / -1

To observe diffraction the size of an aperture :–

A
should be of the same order as wavelength

B
should be much larger than the wave length

C
have no relation to wavelength

D
should be exactly
Question 3
4 / -1

A projectile is projected with velocity kv_e in vertically upward direction from the ground into the space. (v_e is escape velocity and k < 1). If air resistance is considered to be negligible then the maximum height from the centre of earth to which it can go, will be : (R = radius of earth) :-

A
R / k²+1

B
R / k²-1

C
R / 1-k²

D
R / k+1

Solution
Question 4
4 / -1

Suppose, the acceleration due to gravity at the earth's surface is 10 m/s² and at the surface of Mars it is 4.0m/s². A 60 kg passenger goes from the earth to the mars in a spaceship moving with a constant velocity. Neglect all other objects in the sky. Which part of figure best represents the weight (net gravitational force) of the passenger as a function of time :

A
A

B
B

C
C

D
D

Solution

g = Gm / R². If mass remains constant then g ∝ 1/R² % increase in g = 2(% decrease in R) = 2 × 1% = 2%.
Question 5
4 / -1

200 Ω resistance and 1H inductance are connected in series with an A.C. circuit. The frequency of the source is 200/ 2π Hz. Then phase difference in between V and I will be :-

A
30°

B
60°

C
45°

D
90°

Solution
Question 6
4 / -1

A galvanometer having a coil resistance of 60 Ω shows full scale deflection when a current of 1.0 A passes through it. It can be converted into an ammeter to read currents upto 5.0 A by:-

A
putting in parallel a resistance of 15 Ω

B
putting in parallel a resistance of 240 Ω

C
putting in series a resistance of 15 Ω

D
putting in series a resistance of 240 Ω

Solution
Question 7
4 / -1

Two charges q₁ and q₂ are placed 30 cm apart, as shown in the figure. A third charge q₃ is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is k, where k is :-

A
8q₂

B
6q₂

C
8q₁

D
6q₁

Solution

ΔU = U_f – U_i
Question 8
4 / -1

An ideal gas is expanding such that PT² = constant. The coefficient of volume expansion of the gas is:-

A
1 / T

B
2 / T

C
3 / T

D
4 / T

Solution
Question 9
4 / -1

Two straight metallic strips each of thickness t and length L are riveted together. Their coefficient of linear expansions are α₁ and α₂ . If they are heated through temperature ΔT the bimetallic strip will bend to form an arc of radius proportional to :-

A

B

C
t(α₁ + α₂)ΔT

D
None

Solution
Question 10
4 / -1

A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by 62°C, the Efficiency of the engine is doubled. The temperatures of the source and sink are :-

A
80°C, 37°C

B
95°C, 28°C

C
90°C, 37°C

D
99°C, 37°C

Solution