Light with an energy flux of 18W/cm² falls on a non-reflecting surface at normal incidence. The pressure exerted on the surface is:

1) 2N/m²
2) 2 × 10⁻⁴ N/m²
3) 6 N/m²
4) 6 × 10⁻⁴ N/m²

Two identical piano wires have a fundamental frequency of 600 vib/sec, when kept under the same tension. What fractional increase in the tension of one wire will lead to the occurrence of six beats per second when both wires vibrate simultaneously.

1) 0.04
2) 0.01
3) 0.02
4) 0.08

The weight based ratio of $$U^{238}$$ and $$Pb^{226}$$ in a sample of rock is 4 : 3. If the half life of $$U^{238}$$ is $$4.5 \times 10^9$$ years, then the age of rock is:

1) $$9.0 \times 10^9$$
2) $$6.3 \times 10^9 years$$
3) 1$$4.5 \times 10^9 years$$
4) $$3.78 \times 10^9 years$$

A capacitor of 2.5 µf is charged through a resistor of 4mÙ. In how much time will potential drop across capacitor will become 3 times that of resistor (l n 2 = 0.693)

A block of mass 1 kg moving with a speed of 4 m/s, collides with another block of mass 2 kg which is at rest. The lighter block comes to rest after collision. The loss in the kinetic energy of the system is:
1.8 J
2. 4 J
3. 6 J
4. 10 J

A magnet of magnetic moment M is lying in a magnetic field of induction B. W1 is the work done in turning it from 0^o to 60^o and W₂ is the work done in turning it from 30^o to 90^o.Then

1) W₂ =W_1/2
2) W₂ = 2 W_1^?
3) W₂ = W₁
4) W₂ = √3W1

 An isolated conductor will become polarized (in terms of charge) when:

(1) it is touched by a charged object.

(2) it is warmed.

(3) it is brought close to (but not touching) a charged object.

(4) it is charged with a power supply

The electron in a hydrogen atom makes a transition n₁→n₂, where n₁ and n₂ are the principal quantum numbers of the two states. Assume the Bohr model as valid in this case. The frequency of the orbital motion of the electron in the initial state is 1 / 27 of that in the final state. The possible values of n₁ and n₂ are

1) n₁=6,n₂=3
2) n₁=4,n₂=2
3) n₁=8,n₂=1
4) n₁=3,n₂=1

 The relation between current and maximum current Im at half power points in resonant circuit will be :

(1) I = Im / 2√2

(2) I = Im √2

(3) I = Im  / 2

 (4) I = Im / √2

A diode can be used for:

(1) Rectification
(2) Detection
(3) Modulation
(4) Amplification