Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Radioactivity was discovered by

(a) Becquerel

(b) Pierre Curie

(c) Roentgen

(d) Rutherford

A parallel plate capacitor is made of two dielectric blocks in series. One of the blocks has thickness d₁ and dielectric constant k₁ and the other has thickness d₂ and dielectric constant k₂ as shown in Fig.

This arrangement can be thought as a dielectric slab of thickness d (= d₁ + d₂) and effective dielectric constant k. The k is

Two sources give interference pattern which is observed on a screen, D distance apart from the sources. The fringe width is 2w. If the distance D is now doubled, the fringe width will

(a) Become w/2

(b) Remain the same

(c) Become w

(d) Become 4w

One metre length of wire carries a constant current. The wire is bent to form a circular loop. The magnetic field at the centre of this loop is B. The same is now bent to form a circular loop of smaller radius to have four turns in the loop. The magnetic field at the centre of this new loop is

(a) 4 B

(b) 16 B

(c) B/2

(d) B/4

Einstein was awarded a Noble Prize for:

Capacitiors are used in electrical circuits where appliances need more:

An ionic atom equivalent to hydrogen atom has wavelength equal to 1/4 of the wavelengths of hydrogen lines. The ion will be

(a)

(b)

(c)

(d)

The relation between n₁ and n₂, if behaviour of light rays is as shown in figure is

(a)

(b)

(c)

(d)

A charged particle is moved along a magnetic field line. The magnetic force on the particle is: