Physics Test 132

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Physics Test 132

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Question 1
4 / -1

Water is filled up to a height 'h' in a cylindrical vessel. Now, a hole of area 'A' is made at bottom of the vessel. Water drains out of the hole in time 't' seconds. If we repeat the above process with a height of water as '4h', then how much time it require for water to drain out of the cylinder?
[Assume A << A₀ (area of tank)]

A
t seconds

B
4t seconds

C
2t seconds

D
t/4 seconds

Solution

Time required to empty the tank
Question 2
4 / -1

Which of the following graphs correctly represent the variation of β = −[(dV/dp)/V] with p for an ideal gas at constant temperature?

A

B

C

D

Solution

PV = constant, according to Boyle’s law
∴ PV = constant
∴ PdV + VdP = 0

The equation between β and P is of the form xy = constant which represents a rectangular hyperbola.
∴ Graph between β and P will be a rectangular hyperbola represented by graph (a)
Question 3
4 / -1

What is the potential difference between A and B?

(where A is the centre of left ring and B is the centre of right ring)

A

B

C
zero

D

Solution
Question 4
4 / -1

Half-life of a radioactive substance A is 4 days. The probability of a nucleus that, from the given sample that it will decay in two half-lives is

A
1/4

B
3/4

C
1/2

D
1

Solution

After two half-lives 1/4 th fraction of nuclei will remain undecayed. Or, 3/4 th fraction will decay. Hence, the probability that a nucleus decays in two half lives is 3/4
Question 5
4 / -1

Which of the following statement is false for electromagnetic waves ?

A
Both electric and magnetic field vectors attain the maxima and minima at the same place and at the same time.

B
The energy in electromagnetic wave is divided equally between electric and magnetic fields.

C
Both electric and magnetic field vectors are perpendicular to each other and perpendicular to the direction of propagation of wave.

D
These waves cannot propagate in a material medium.

Solution

Electromagnetic waves can propagate in material as well as vacuum.
Question 6
4 / -1

The voltage of clouds is 4 × 10⁶ V with respect to ground. In a lightning strike lasting 100 ms, a charge of 4 C is delivered to the ground. The average power of lightning strike is (assume complete discharges)

A
160 MW

B
80 MW

C
20 MW

D
500 KW

Solution

Energy stored between cloud and earth, assuming the capacitor model is
Question 7
4 / -1

A tuning fork vibrates with a frequency of 256 Hz. Taking the speed of sound to be 345.6 m s^-1 in the air, find the wavelength and the distance, which the sound travels during the time, fork makes 60 vibrations.

A
1.35 m, 81 m

B
1.40 m, 84 m

C
1.45 m, 87 m

D
1.55 m, 93 m

Solution

In one cycle, sound advances by distance λ
Therefore, the required distance travelled by sound,
S = 60. λ = 81 m
Question 8
4 / -1

If the radius of the earth were to shrink by one percent and its mass remains the same, the acceleration due to gravity on the earth's surface would

A
Decrease

B
Remain unchanged

C
Increase

D
Become zero

Solution

g = GM/R²
or g∝1/R²
g will increase if R decreases.
Question 9
4 / -1

Six wires of current I₁ = 1A, I₂ = 2A, I₃ = 3A, I₄ = 1A, I₅ = 5A and I₆ = 4A cut the page perpendicularly at the points 1,2,3,4,5 and 6 respectively as shown in the figure. Find the value of integral ∮B→.dℓ around the circular path c.

A
6μ₀weber.m⁻¹

B
μ₀ weber.m⁺¹

C
μ₀ weber.m⁻¹

D
5μ₀ weber.m

Solution
Question 10
4 / -1

Three capacitors each of capacity 4 μF are to be connected in such a way that the effective capacitance is 6 μF. This can be done by

A
Connecting all of them in series

B
Connecting all of them in parallel

C
Connecting two in series and one in parallel with the series combination

D
Connecting two in parallel and one in series with the parallel combination

Solution

To get equivalent capacitance 6 μF Out of the 4 μF capacitance, two are connected in series and third one is connected in parallel.