An electron of mass m and charge e is accelerated from rest through a potential difference of V volt in a vacuum. Its final speed will be ______________.

(a)

\(\frac { eV }{ 2m } \)

(b)

\(\frac { eV }{ m } \)

(c)

\(\sqrt { \frac { 2eV }{ m } } \)

(d)

\(\sqrt { \frac { eV }{ 2m } } \)

Einstein's work on photoelectric effect gives support to _______________.

(a)

E = mc²

(b)

E=hv

(c)

hg-\(\frac{1}{2}\) mv²

(d)

E=\(\frac { h }{ \lambda } \)

Gases begin to conduct electricity at low pressure because ______________.

(a)

at low pressure gases turn to plasma

(b)

colliding electrons can acquire higher K.E due to increased mean free path leading to ionisation of atoms

(c)

atoms breakup into electrons and protons

(d)

the electrons in atoms can move freely at low pressure

The value of stopping potential when the frequency of light is equal to the threshold frequency is _________________.

(a)

maximum

(b)

zero

(c)

minimum

(d)

infinity

According to special theory of relativity the only constant in all frames is _____________.

(a)

mass

(b)

length

(c)

time

(d)

velocity of light