A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 a.m.u. The energy liberated per a.m.u. is(Given : 1 a.m.u = 931 MeV)

26.7 MeV
6.675 MeV
13.35 MeV
2.67 MeV

Solution

In the displacement method, a concave lens is placed in between an object and a screen. If the magnification in the two positions are m₂and m₂(m₁ > m₂), and the distance between the two positions of the lens is x, the focal length of the lens is

\(\frac{x}{m_{1}+m_{2}}\)
\(\frac{x}{m_{1}-m_{2}}\)
\(\frac{x}{(m_{1}+m_{2})^{2}}\)
\(\frac{x}{(m_{1}-m_{2})^{2}}\)

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

Statement 1: Optical fibres are used to transmit light without any appreciable loss in its intensity over distance of several kilometers.

Statement 2: Optical fibres are very thick and all the light is passed through it without any loss.

(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

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

A train of 150 m length is going towards north direction at a speed of 10 ms^-1. A parrot flies at a speed of 5 ms^-1 to wards south direction parallel to the railway track. The time taken by the parrot to cross the train is equal to

12 s
8 s
15 s
10 s

Solution

So by figure the velocity of parrot w.r. t. train is = 5–(–10) = 15m/sec

so time taken to cross the train is

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

Statement 1 : Radio waves can be polarised.

Statement 2 :Sound waves in air are longitudinal in nature.

(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

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

Radio waves can be polarised because they are transverse in nature. Sound waves in air are longitudinal in nature.

A coil of self-inductance L is connected in series with a bulb Band an AC source. Brightness of the bulb decreases when

number of turns in the coil is reduced
a capacitance of reactance X_C = X_L is included in the same circuit
an iron rod is inserted in the coil
frequency of the AC source is decreased

Solution

A diamagnetic material in a magnetic field moves

perpendicular to the field
from stronger to the weaker parts of the field
from weaker to the stronger parts of the field
None of these

Solution

A diamagnetic material in a magnetic field moves, from stronger to the weaker parts of the field.

Barrier potential of a P-N junction diode does not depend on

doping density
diode design
temperature
forward bias

Solution

[Hint : Barrier potential depends on, doping density,temperature, forward/reverse bias but does not depend on diode design.]

A 2 m long rod of radius 1 cm which is fixed from one end is given a twist of 0.8 radian. The shear strain developed will be

0.002
0.004
0.008
0.016

Solution

ɸ = \(\frac{r\Theta }{\iota }=\frac{1}{100}\times \frac{0.8}{2}= 0.004\: radian\)

A pendulum is under going S.H.M. The velocity of the bob in the mean position is v. If now its amplitude is doubled,keeping the length same,its velocity in the mean position will be

Solution

V_max=aω;V'_max=2aω=2V_max=2v
(since v_max=v)

A particle covers half of the circle of radius r. Then the displacement and distance of the particle are respectively

2πr,0
2r,πr
^π⁄₂
πr,r

Solution

When a particle cover half of circle of radius r, then displacement is AB = 2r & distance = half of circumference of circle = πr

A mixture consists of two radioactive materials A₁ and A₂ with half lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A₁ and 160 g of A₂. The amount of the two in the mixture will become equal after

60 s
80 s
20 s
40 s

Solution

A vessel contains air at a temperature of 15º C and 60 % R.H.What will be the R.H. if it is heated to 20º C? (S.V.P. at 15º C is 12.67 & at 20º C is 17.36 mm of Hg respectively)

262 %
26.2 %
44.5 %
46.2 %

Solution

A wheel is rolling straight on ground without slipping. If the axis of the wheel has speed v, the instantenous velocity of a point P on the rim, defined by angle θ, relative to the ground will be

v cos(¹⁄₂ θ)
2v cos(¹⁄₂ θ)
v (1 + sin θ)
v (1 + cos θ)

Solution

A vessel has 6g of hydrogen at pressure P and temperature 500K. A small hole is made in it so that hydrogen leaks out.How much hydrogen leaks out if the final pressure is P/2 and temperature falls to 300 K ?

Solution

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