220 V, 50 Hz, AC source is connected to an inductance of 0.2 Hand a resistance of 20 Ω in series. Whatis the current in the circuit?

• 3.33 A

• 33.3 A

• 5 A

• 10 A

If we change the value of R, then

• voltage does not change on L

• voltage does not change on LC combination

• voltage does not change on C

• voltage changes on LC combination

Real power consumption in a circuit is least when it contains.

• high R, low L

• high R, high L

• low R, high L

• high R, low C

The rms speed (in m/s) of oxygen molecules of the gas at temperature 300 K, is

• 483

• 504

• 377

• 346

An inductor (L = 20 H), a resistor (R = 100 Ω) and a battery (E = 10 V) are connected in series. After a long time, the circuit is short-circuited and then the battery is disconnected. Find the current in the circuit at 1 ms after short circuiting.

• 4.5 x 10⁵ A

• 3.2x 10^-5 A

• 9.8 × 10^-5 A

• 6.7 × 10^-4 A

The magnetic flux through each turn of a coil having 200 turns is given as (t² $-$ 1) x 10^-3 Wb, where t is in second. The emf induced in the coil at t = 3s is

• 0.7 V

• 1.2 V

• 0.8 V

• 0.9 V

137.

A beam of light travelling along X-axis is described by the electric field E_v = 600 $\frac{\mathrm{V}}{\mathrm{m}}$. sin$\mathrm{\omega } \left(\mathrm{t} - \frac{\mathrm{x}}{\mathrm{c}}\right)$, the maximum magnetic force on a charge q = 2e, moving along Y-axis with the speed of 3 × 10⁸ m/s is 

• 19.2 × 10^-17 N

• 1.92 × 10^-17

• 0.192

• None of these

An L-C-R series circuit with a resistance of 100 Ω is connected to 200 V (AC source) and angular frequency 300 rad/s. When only the capacitor is removed, then the current lags behind the voltage by 60°. When only the inductor is removed the current leads the voltage by 60°. The average power dissipated in original L-C-R circuit is

• 50 W

• 100 W

• 200 W

• 400 W

In an LCR circuit as shown in figure, both switches are open initially. Now switch S₁ is closed, S₂ kept open. (q is charge on the capacitor and τ = RC is capacitive time constant). Which of the following statement is correct?       

• At t = $\frac{\mathrm{\tau }}{2}$, q = CV ( 1 $-$ e^-1 )

• Work done by the battery is half of the energy dissipated in the resistor

• At t = τ, q = CV/2

• At t = τ, q = CV ( 1 $-$ e^-2 )

A circular coil of radius 10 cm, 500 turns and resistance 2 Ω is placed with its plane perpendicular to the horizontal component of the earth's magnetic field. It is rotated about its vertical diameter through 180° in 0.25 s. The
current induced in the coil is

(Horizontal component of the earth's magnetic field at that place is 3.0 x 10^-5 T)

• 1.9 × 10^-3 A

• 2.9 × 10^-3 A

• 3.9 × 10^-3 A

• 4.9 × 10^-3 A