The momentum of photon whose frequency f is

\(\frac{hf}{c}\)
\(\frac{hc}{f}\)
\(\frac{h}{f}\)
\(\frac{c}{hf}\)

Solution

The transmitting antenna of a radiostation is mounted vertically. At a point 10 km due north of the transmitter the peak electric field is 10^–3Vm^–1. The magnitude of the radiated magnetic field is

3.33 × 10^–10 T
3.33× 10^–12 T
10^–3 T
3 × 10⁵ T

Solution

The frequency response curve of RC coupled amplifier is shown in figure. The band with of the amplifier will be

f₃ – f₂
f₄ – f₁
\(\frac{f_{4}-f_{2}}{2}\)
f₃ – f₁

Doubly ionised helium atom and hydrogen ions are accelerated, from rest, through the same potential difference.The ratio of final velocities of helium and hydrogen is

1 :√2
√2 : 1
1 : 2
2 : 1

Solution

A body of mass m falls from a height h onto a pan (of negligible mass) of a spring balance as shown. The spring also possesses negligible mass and has spring constant k.Just after striking the pan, the body starts socillatory motion in vertical directioin of amplitude A and energy E. Then

A=^mg⁄_k
\(A=\frac{mg}{k\sqrt{1+\frac{2kh}{mg}}}\)
\(E=mgh+\frac{1}{2}kA^{2}\)
\(E=mgh+\frac{1}{2}kA^{2}\)

Solution

DIRECTIONS : Each question contains Statement-1 and Statement-2. Choose the correct answer(ONLY ONE option is correct ) from the following.

Statement -1 : If collision occurs between two elastic bodies their kinetic energy decreases during the time of collision.

Statement -2 : During collision inter molecular space decreases and hence elastic potential energy increases

(a)Statement -1 is false, Statement-2 is true
(b)Statement -1 is true, Statement-2 is true;Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement -2 is not a correct explanation for Statement-1
(d)Statement -1 is true, Statement-2 is false

Solution

(b)Statement -1 is true, Statement-2 is true;Statement -2 is a correct explanation for Statement-1

In Young’s double slit experiment, the slits are 2 mm apart and a reilluminated by photons of two wavelengths λ₁= 12000 Å and λ₂= 10000 Å. At what minimum distance from the common central bright fringe on the screen 2 m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other ?

6 mm
4 mm
3 mm
8 mm

Solution

Direction: Each question contains STATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following.

(a)Statement -1 is false, Statement-2 is true

(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1

(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1

(d)Statement -1 is true, Statement-2 is false

Statement 1 : The magnetic field at the centre of the circular coil in the following figure due to the currents I₁ and I₂ is zero.

Statement 2: I₁= I₂ implies that the fields due to the current I₁ and I₂ will be balanced.

View Ans & Explanation
(d)Statement -1 is true, Statement-2 is false

A body of mass 4 kg moving on a horizontal surface with an initial velocity of 6 ms^-1 comes to rest after 3 seconds. If one wants to keep the body moving on the same surface with the velocity of 6 ms^-1, the force required is

Zero
4 N
8 N
16 N

Solution

Acceleration,a=\(\frac{v-u}{t}=\frac{0-6}{3}=-2\: ms^{-2}\)

Force = m×a = 4×2 = 8 N

A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is

Ec
2E/c
E/c
E/c²

Solution

Momentum of photon = ^E⁄_C

Change in momentum = ^2E⁄_C

momentum transferred to the surface(the photon will reflect with same magnitude of momentum in opposite direction).

An AC voltage source has an output of V= 200 sin 2πft.This source is connected to a 100 Ω resistor. RMS currentin the resistance is

1.41 A
2.41 A
3.41 A
0.71 A

A balloon starts rising from the ground with an acceleration of 1.25 ms^-2. After 8 s, a stone is released from the balloon.The stone will (Taking g = 10 m s^-2)

begin to move down after being released
reach the ground in 4s
cover a distance of 40 m in reaching the ground
will have a displacement of 50 m.

Solution

v =1.25 × 8 ms^-1= 10 ms^-1

s=¹⁄₂ × 1.25 × 8 × 8m= 40m

Now , 40= -10t + ¹⁄₂ × 10 × t²

or 5t² - 10t - 40 = 0

or t² -2t - 8 = 0 or t =4 s.

Two vectors A and B lie in a plane, another vector C lies out side this plane, then the resultant of these three vectors i.e., A+ B + C

can be zero
cannot be zero
lies in the plane containing A+ B
lies in the plane containing A– B

A heater of 220 V heat a volume of water in 5 minutes time.A heater of 110 V heats the same volume of water in

5 minutes
8 minutes
10 minutes
20 minutes

Solution

Heat produced, .H = ^V²t⁄_R.When voltage is halved,the heat produced becomes one fourth. Hence time taken to heat the water becomes four time.

The top of an insulated cylindrical container is covered by a disc having emissivity 0.6 and conductivity 0.167WK^-1m^-1 and thickness1 cm. The temperature is maintained by circulating oil as shown in figure. Find the radiation loss to the surrounding in Jm^-2s^-1 if temperature of the upper surface of the disc is 27°C and temperature of the surrounding is 27°C

595 Jm^-2s^-1
545 Jm^-2s^-1
495 Jm^-2s^-1
None of these

Solution

The rate of heat loss per unit area due to radiation

= ∈σ(T⁴–T₀⁴)

= 0.6 × 5.67 × 10^-8[(400)⁴–(300)⁴] = 595 Jm^–2s^-1
.

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