In photoelectric emission, a radiation whose frequency is 4 times threshold frequency of a certain metal is incident on the metal. Then the maximum possible velocity of the emitted electron will be _____.

(a)

\(\sqrt { \frac { { hv }_{ o } }{ m } } \)

(b)

\(\sqrt { \frac { { 6hv }_{ o } }{ m } } \)

(c)

\(2\sqrt { \frac { { hv }_{ o } }{ m } } \)

(d)

\(\sqrt { \frac { { hv }_{ o } }{2m } } \)

A light source of wavelength 520 nm emits 1.04 x 10¹⁵ photons per second while the second source of 460 nm produces 1.38 x 10¹⁵ photons per second. Then the ratio of power of second source to that of first source is _____.

(a)

1.00

(b)

1.02

(c)

1.5

(d)

0.98

The threshold wavelength for a metal surface whose photoelectric work function is 3.313 eV is _____.

(a)

4125 \(\mathring { A } \)

(b)

3750\(\mathring { A } \)

(c)

6000\(\mathring { A } \)

(d)

2062.5\(\mathring { A } \)

Photons of wavelength λ are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of radius R by a perpendicular magnetic field having magnitude B. The work function of the metal is _____.

(a)

\(\frac { hc }{ \lambda } -{ m }_{ e }+\frac { e^{ 2 }{ B }^{ 2 }{ R }^{ 2 } }{ { 2m }_{ e } } \)

(b)

\(\frac { hc }{ \lambda } +{ 2m }_{ e }{ \left[ \frac { eBR }{ { 2m }_{ e } } \right] }^{ 2 }\)

(c)

\(\\ \frac { hc }{ \lambda } -{ m }_{ e }{ c }^{ 2 }-\frac { e^{ 2 }{ B }^{ 2 }{ R }^{ 2 } }{ { 2m }_{ e } } \)

(d)

\(\frac { hc }{ \lambda } -{ 2m }_{ e }{ \left[ \frac { eBR }{ { 2m }_{ e } } \right] }^{ 2 }\)

Emission of electrons by the absorption of heat energy is called ______ emission.

(a)

photoelectric

(b)

field

(c)

thermionic

(d)

secondary