Nuclei — Physics STD 12 Science — Question

The propagation constant of a photon of wavelength 6284 A°.

A bar magnet of magnetic moment 3.0 A-m² is placed in a uniform magnetic induction field of 2 × 10^–5 T. If each pole of the magnet experiences a force of 6 × 10^–4 N, the length of the magnet is

(a) 0.5 m

(b) 0.3 m

(c) 0.2 m

(d) 0.1 m

Which one of the following is not a unit of magnetic field ?

Two bulbs each marked 100 W, 220 V are connected in series across 220 V supply. The power consumed by them, when lit, is

The rate of change of magnetic flux density through a circular coil of area 10m and number of turns 100 is 10³ Wb/ m²/ s. The value of induced emf will be.

A 40 mF capacitor in a defibrillator is charged to 3000 V. The energy stored in the capacitor is sent through the patient during a pulse of duration 2ms. The power delivered to the patient is

(a) 45 kW

(b) 90 kW

(c) 180 kW

(d) 360 kW

The light source will be coherent if :

A cathode emits 1.8  electrons per second, when heated. When 400V is applied to anode all the emitted electrons reach the anode. The charge on electron is 1.6 . The maximum anode current is

(a) 2.7 μA

(b) 29 μA

(c) 72 μA

(d) 29 μA

In the ideal double-slit experiment, when a glass-plate (refractive index 1.5) of thickness t is introduced in the path of one of the interfering beams (wavelength l), the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is

(a) 2l

(b)

(c)

(d)

Electrostatic is the branch of physics which deals with the: