Atoms — Physics STD 12 Science — Question

Dielectric constant for metal is

(a) Zero

(b) Infinite

(c) 1

(d) Greater than 1

The phase difference between incident wave and reflected wave is 180° when light ray

(a) Enters into glass from air	(b) Enters into air from glass
(c) Enters into glass from diamond	(d)  Enters into water from glass

The wavelength of sodium light in air is 5890 Å. The velocity of light in air is 3  The wavelength of light in a glass of refractive index 1.6 would be close to

(a) 5890 Å

(b) 3681 Å

(c) 9424 Å

(d) 15078 Å

What inferences were drawn from Oersteds experiment?

An electric dipole has the magnitude of its charge as q and its dipole moment is p. It is placed in a uniform electric field E. If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively

(a) 2q.E and minimum

(b) q.E  and p.E

(c) Zero and minimum

(d) q.E and maximum

In the following Wheatstone bridge P/Q = R/S. If key K is closed, then the galvanometer will show deflection

(a) In left side

(b) In right side

(c) No deflection

(d) In either side

When a beam of accelerated electrons hits a target, a continuous X-ray spectrum is emitted from the target. Which of the following wavelength is absent in the X-ray spectrum, if the X-ray tube is operating at 40,000 volts

(a) 0.25 Å

(b) 0.5 Å

(c) 1.5 Å

(d) 1.0 Å

An electron and a proton are both released from rest 1 meter from a large stationary negative charge, considering only the force from the large stationary negative charge on the proton and electron. Which of the following is true?

Sodium and copper have work functions 2.3 eV and 4.5 eV respectively. Then the ratio of the wavelengths is nearest to?

Calculate the wavelength of electromagnetic waves of frequency 300MHz.