In a hydrogen atom the electron revolves around the proton in an orbit of 0.53 \(\mathring { A } \). The potential produced by the electron on the nuleus is ___________

(a)

6.8 V

(b)

13.6 V

(c)

54.4 V

(d)

27.2 V

If the specific resistance of a potentiometer wire is 10^-7 Om and current flowing through it is 0.1 amp, cross-sectional area of wire is 10^-6 m², then potential gradient will be ________________.

(a)

10^-2 v/m

(b)

10^-4 v/m

(c)

10^-6 v/m

(d)

10^-8v/m

The reciprocal of conductivity is________

(a)

specific conductance

(b)

specific resistance

(c)

resistance

(d)

conductance

The direction of the magnetic force on a positive charge moving in a magnetic field is given by ________________.

(a)

thumb rule

(b)

left hand rule

(c)

right hand rule

(d)

cork screw rule

Electric filament lamp gives rise to _______________spectrum.

(a)

line 

(b)

band

(c)

continuous

(d)

absorption

A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm, The image will from at ______________.

(a)

Infinity behind the mirror

(b)

Focus

(c)

Pole

(d)

15 cm

The phenomena by which metals emit electrons under the influence of radiation is called ________

(a)

interference

(b)

polarization

(c)

ionization

(d)

photoelectric effect

If R is Rydberg's constant, the minimum wavelength of hydrogen spectrum is _____________.

(a)

1/R

(b)

R/4

(c)

4/R

(d)

R

Natural uranium consists of _____________ % of U₂₃₅ and __________% of U₂₃₈

(a)

0.72, 99.28

(b)

99.28, 0.72

(c)

77.28, 72

(d)

72, 77.28

Which statement is incorrect regarding for p-n junction?

(a)

Donor atoms are depleted of their holes in junction

(b)

No net charge exists far from junction

(c)

Barrier potential V_B is generated

(d)

Energy V_B is to be surrounted before any charge can flow across junction