Ray Optics and Optical Instruments — Physics STD 12 Science — Question

When a straight wire is moved up and down rapidly between two poles of a horseshoe magnet then _______ is produced in the wire.

The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 mT. What will be its value at the centre of the loop

(a) 250 m T

(b) 150 m T

(c) 125 m T

(d) 75 m T

The fluorescence of the glass (discharge) tube at very low pressure is characteristic of ________:

Two photons having:

1. Equal wavelengths have equal linear momenta.
2. Equal energies have equal linear momenta.
3. Equal frequencies have equal linear momenta.
4. Equal linear momenta have equal wavelengths.

What is the order of potential difference built up by the Van de Graff generator?

Bonds in semiconductors are :

For the diode, the characteristic curves are given at different temperature. The relation between the temperatures is

(a)

(b)

(c)

(d) None of the above

What is the work done by the magnetic field on the moving charge?

The energy of hydrogen atom in its ground state is – 13.6 eV. The energy of the level corresponding  to the quantum number n is equal 5 is

(a) – 5.40 eV

(b) – 2.72 eV

(c) – 0.85 eV

(d) – 0.54 eV

An electromagnetic wave propagating along north has its electric field vector upwards. Its magnetic field vector point towards.