Which charge configuration produces a uniform electric field?

(a)

point charge

(b)

uniformly charged infinite line

(c)

uniformly charged infinite plane

(d)

uniformly charged spherical shell

Two identical conducting balls having positive charges q₁ and q₂ are separated by a centre to centre distance r. If they are made to touch each other and then separated to the same distance, the force between them will be _____.

(a)

less than before

(b)

same as before

(c)

more than before

(d)

zero

A parallel plate capacitor stores a charge Q at a voltage V. Suppose the area of the parallel plate capacitor and the distance between the plates are each doubled then which is the quantity that will change?

(a)

Capacitance

(b)

Charge

(c)

Voltage

(d)

Energy density

A wire connected to a power supply of 230 V has power dissipation P₁. Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case power dissipation is P₂. The ratio \(\frac{P_2}{P_1}\) is ______.

(a)

1

(b)

2

(c)

3

(d)

4

A thin insulated wire forms a plane spiral of N = 100 tight turns carrying a current I = 8 m A (milli ampere). The radii of inside and outside turns are a = 50 mm and b = 100 mm respectively. The magnetic induction at the centre of the spiral is ______.

(a)

\(5\mu T\)

(b)

\(7\mu T\)

(c)

\(8\mu T\)

(d)

\(10\mu T\)

The flux linked with a coil at any instant t is given by \(\Phi\)_B = 10t² − 50t + 250. The induced emf at t = 3s is

(a)

−190 V

(b)

−10 V

(c)

10 V

(d)

190 V

In an oscillating LC circuit, the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic fields is

(a)

\(\frac{Q}{2}\)

(b)

\(\frac{Q}{\sqrt3}\)

(c)

\(\frac{Q}{\sqrt2}\)

(d)

Q

Consider an oscillator which has a charged particle oscillating about its mean position with a frequency of 300 MHz. The wavelength of electromagnetic waves produced by this oscillator is _____.

(a)

1 m

(b)

10 m

(c)

100 m

(d)

1000 m

If E = E_o sin[10⁶ x -ωt] be the electric field of a plane electromagnetic wave, the value of ω is_____.

(a)

0.3 x 10⁻¹⁴ rad s⁻¹

(b)

3 x 10⁻¹⁴ rad s⁻¹

(c)

0.3 x 10¹⁴ rad s⁻¹

(d)

3 x 10¹⁴ rad s^-1

If the velocity and wavelength of light in air is V_a and λ_a and that in water is V_w and λ_w, then the refractive index of water is______.

(a)

\(\frac{V_W}{V_a}\)

(b)

\(\frac{V_a}{V_W}\)

(c)

\(\frac{\lambda_W}{\lambda_a}\)

(d)

\(\frac{{V_a}\lambda_a}{{V_W}\lambda_W}\)

The wave associated with a moving particle of mass 3 x 10^–6 g has the same wavelength as an electron moving with a velocity 6 x 10⁶ ms^-1. The velocity of the particle is _____.

(a)

1.82 x 10^-18ms^-1

(b)

9 x 10^-2ms^-1

(c)

3 x 10^-31ms^-1

(d)

1.82 x 10^-15ms^-1

The threshold wavelength for a metal surface whose photoelectric work function is 3.313 eV is _____.

(a)

4125 \(\mathring { A } \)

(b)

3750\(\mathring { A } \)

(c)

6000\(\mathring { A } \)

(d)

2062.5\(\mathring { A } \)

In J.J. Thomson e/m experiment, electrons are accelerated through 2.6 kV enter the region of crossed electric field and magnetic field of strength 3.0 x 10⁴ Vm^-1 and 1.0 x 10^-3 T, respectively, and pass through it and undeflected, then the specific charge is _____.

(a)

1.6 × 10¹⁰ C kg^–1

(b)

1.7 × 10¹¹ Ckg^–1

(c)

1.5 × 10¹¹ Ckg^–1

(d)

1.8 × 10¹¹ Ckg^–1

A radiative element has N₀ number of nuclei at t = 0. The number of nuclei remaining after half of a half-life _____.(that is, at time t = \(\frac{1}{2}T_\frac{1}{2}\))

(a)

\(\frac{N_0}{2}\)

(b)

\(\frac{N_0}{\sqrt2}\)

(c)

\(\frac{N_0}{4}\)

(d)

\(\frac{N_0}{8}\)

When light is incident on a soap film of thickness 5 x 10^–5 cm, the wavelength of light reflected maximum in the visible region is 5320 Å. Refractive index of the film will be, _____.

(a)

1.22

(b)

1.33

(c)

1.51

(d)

1.83