A parallel plate condenser has uniform electric field E(V/m) in the space between the plates. if the distance between the plates is d(m) and area of each plate is A(m²) the energy (joules) stored in the condenser is.

• E²Ad / ε₀

• ε₀EAd

• ½ (ε₀ E²)

• ½ ( ε₀ E² Ad)

When hydrogen atom is in its first excited level its radius is.

• Four times its ground state radius

• Same

• Twice

• Three times

• 3.4 eV

• 10.2 eV

• 12.1 eV

• 13.6 eV

Energy of electron in a orbit of H-atom is

• Positive

• Negative

• Zero

• Nothing can be said

X-rays of λ=1A° have frequency

• 3×10⁸Hz

• 3×10¹⁸Hz

• 3×10¹⁰Hz

• 3×10¹⁵Hz

How is the potential within and on the surface of a conductor?

• Indirectly proportional

• Directly proportional

• Zero

• Constant

The diagram shows the electric field lines in a region of space containing two small

charged spheres (Y and Z). Then

• Y is negative and Z is positive

• The magnitude of the electric field is the same everywhere

• The electric field is strongest midway between Y and Z

• The electric field is not zero anywhere (except infinitely far from the spheres)

A cell of emf 5V and internal resistance 1 Ω will give maximum power output to

• A single resistor of 1 Ω

• Two 1 Ω resistor connected in series

• Two 1 Ω resistor connected in parallel

• None of these

A charged particle enters a magnetic field such that the direction of initial velocity is different from the direction of the field. Which of the following characteristics of the particle will not change with time?

• Momentum

• Acceleration

• Kinetic energy

• Direction of motion

Figures show some equipotential lines distributed in space. A charged object is moved from point A to point B.

• The work done in Fig. (i) is the greatest.

• The work done in Fig. (ii) is least.

• The work done is the same in Fig. (i), Fig.(ii) and Fig. (iii).

• The work done in Fig. (iii) is greater than Fig. (ii) but equal to that in Fig. (i).