Electric Charges and Fields — Physics STD 12 Science — Question

 Which among the following is the proper way of earthing?

Liquids and gases never exhibit:

The minimum wavelength of X-ray emitted by X-rays tube is 0.4125 Å. The accelerating voltage is

(a) 30 kV

(b) 50 kV

(c) 80 kV

(d) 60 kV

The shortest wavelength in the Lyman series of hydrogen spectrum is 912 Å corresponding to a photon energy of 13.6 eV. The shortest wavelength in the Balmer series is about

(a) 3648 Å

(b) 8208 Å

(c) 1228 Å

(d) 6566 Å

According to kinetic theory of matter, a molecule is the smallest particle of a substance and it possesses :

A bar magnet has a magnetic moment equal to 5 . It is suspended in a magnetic field which has a magnetic induction (B) equal to 8π  tesla. The magnet vibrates with a period of vibration equal to 15 sec. The moment of inertia of the magnet is

(a) 22.5

(b) 11.25

(c) 5.62

(d) 7.16

A photo cell is receiving light from a source placed at a distance of 1 m. If the same source is to be placed at a distance of 2 m, then the ejected electron

(a) Moves with one-fourth energy as that of the initial energy

(b) Moves with one-fourth of momentum as that of the initial momentum

(c) Will be half in number

(d) Will be one-fourth in number

The ground state energy of hydrogen atom is – 13.6 eV. What is the potential energy of the electron in this state

(a) 0 eV

(b) – 27.2 eV

(c) 1 eV

(d) 2 eV

The unit of intensity of electric field is

(a) Newton/Coulomb

(b) Joule/Coulomb

(c) Volt - metre

(d) Newton/metre

A coil develops heat of 800 cal/sec. When 20 volts is applied across its ends. The resistance of the coil is (1 cal = 4.2 joule)

(a) 1.2 Ω

(b) 1.4 Ω

(c) 0.12 Ω

(d) 0.14 Ω