Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A uniform conducting wire ABC has a mass of 10g. A current of 2A flows through it. The wire is kept in a uniform magnetic field B = 2T. The acceleration of the wire will be

(a) Zero	(b) 12  along  y-axis
(c) 1.2  along y-axis	(d) 0.6  along y - axis

If the capacitors in the previous question are joined in parallel, the capacitance and the breakdown voltage of the combination will be:

When air is replaced by a dielectric medium of constant k, the maximum force of attraction between two charges separated by a distance

(a) Decreases k  times	(b) Remains unchanged
(c) Increases k times	(d) Increases  times

The hysteresis cycle for the material of permanent magnet is:

Water flows through two identical tubes A and B. A volume V₀ of water passes through the tube A and 2 V₀ through B in a given time. Which of the followinmay be correct?

1. Flow in both the tubes are steady.
2. Flow in both the tubes are turbulent.
3. Flow is steady in A but turbulent in B.
4. Flow is steady in B but turbulent in A.

 has half life 5700 years. At the end of 11400 years, the actual amount left is

(a) 0.5 of original amount	(b) 0.25 of original amount
(c) 0.125 of original amount	(d) 0.0625 of original amount

An oscillator is producing FM waves of frequency 2 kHz with a variation of 10 kHz. What is the modulating index

(a) 0.20

(b) 5.0

(c) 0.67

(d) 1.5

Light from sodium lamp is passed through cold sodium vapours, the spectrum of transmitted light consists of

(a) A line at 5890 Å	(b) A line at 5896 Å
(c) Sodium doublet lines	(d) No spectral features

A wire has a resistance of 6 W. It is cut into two parts and both half values are connected in parallel. The new resistance is ....

(a) 12 W

(b) 1.5 W

(c) 3 W

(d) 6 W

Two coils A and B having turns 300 and 600 respectively are placed near each other, on passing a current of 3.0 ampere in A, the flux linked with A is 1.2  and with B it is 9.0 . The mutual inductance of the system is

(a) 2 × 10–5 henry

(b) 3 × 10–5 henry

(c) 4 × 10–5 henry

(d) 6 × 10–5 henry