Moving Charges and Magnetism — Physics STD 12 Science — Question

In a coaxial, straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero:

1. Outside the cable.
2. Inside the inner conductor.
3. Inside the outer conductor.
4. In between the tow conductors.

A coil having N turns is wound tightly in the form of a spiral with inner and outer radii a and b respectively. When a current I passes through the coil, the magnetic field at the centre is

(a)

(b)

(c)

(d)

Coulomb force and gravitational force follows the:

A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time period of vibration is found to be 2 seconds. The same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be 2 seconds. Then the angle of dip is

(a) 0o

(b) 30o

(c) 45o

(d) 90o

The wave-like character was experimentally proved for light by:

The capacity of a condenser in which a dielectric of dielectric constant 5 has been used, is  C. If the dielectric is replaced by another with dielectric constant 20, the capacity will become

(a)

(b) 4C

(c)

(d) 2C

In a fission process, nucleus A divides into two nuclei B and C, their binding energies being  and   respectively. Then

(a)

(b)

(c)

(d)

The work functions for sodium and copper are 2eV and 4eV. Which of them is suitable for a photocell with 4000 Å light

(a) Copper

(b) Sodium

(c) Both

(d) Neither of them