Uploaded January 2026 | Updated September 2026, 3 weeks ago
When a photon of suitable frequency is incident on a metal surface photoelectron is emitted from it. If the frequency is below a threshold frequency (νo) for the surface, no photoelectron is emitted. For a photon of frequency v(v 》vo), the kinetic energy of the emitted photoelectrons is h(v - vo). The photocurrent can be stopped by applying a potential Vo. called 'stopping potential' on the anode. Thus maximum kinetic energy of photoelectrons Km = e Vo = h(v - vo). The experimental graph between Vo and v for a metal is shown in figure. This is a straight line of slope m.
(i) The straight line graphs obtained for two metals
(A) coincide each other.
(B) are parallel to each other.
(C) are not parallel to each other and cross at a point on v-axis.
(d) are not parallel to each other and do not cross at point on v-axis
(ii) The value of Planck's constant for this metal is
(A) e/m (B) 1/me
(C) me (D) m/e
(iii) The intercepts on v-axis and Vo-axis of the graph are respectively
(A) vo, hvo/e (B) vo, hvo
(C) hvo/e, vo (D) hvo, vo
or
(iii) When the wavelength of a photon is doubled, how many times its wave number and frequency become, respectively ?
(A) 2, 1/2 (B) 1/2, 1/2
(C) 1/2, 2 (D) 2, 2
(iv) The momentum of a photon is 5.0 x 10-²⁹ kg. m/s. Ignoring relativistic effects (if any), the wavelength of the photon is
(A) 1.33 µm (B) 3.3 µm
(C) 16.6 µm (D) 13.3 µm
Question No. 30- cbse 2025 physics class 12
| solution by ujwal Kumar physics master | physics master academy is best coaching for all physics students.
best physics teacher of neet, JEE-Mains in delhi
Download our app for android and ios on-app.in/app/home?orgCode=vdtxq
When a photon of suitable frequency is incident on a metal surface photoelectron is emitted from it. If the frequency is below a threshold frequency (νo) for the surface, no photoelectron is emitted. For a photon of frequency v(v 》vo), the kinetic energy of the emitted photoelectrons is h(v - vo). The photocurrent can be stopped by applying a potential Vo. called 'stopping potential' on the anode. Thus maximum kinetic energy of photoelectrons Km = e Vo = h(v - vo). The experimental graph between Vo and v for a metal is shown in figure. This is a straight line of slope m.
(i) The straight line graphs obtained for two metals
(A) coincide each other.
(B) are parallel to each other.
(C) are not parallel to each other and cross at a point on v-axis.
(d) are not parallel to each other and do not cross at point on v-axis
(ii) The value of Planck's constant for this metal is
(A) e/m (B) 1/me
(C) me (D) m/e
(iii) The intercepts on v-axis and Vo-axis of the graph are respectively
(A) vo, hvo/e (B) vo, hvo
(C) hvo/e, vo (D) hvo, vo
or
(iii) When the wavelength of a photon is doubled, how many times its wave number and frequency become, respectively ?
(A) 2, 1/2 (B) 1/2, 1/2
(C) 1/2, 2 (D) 2, 2
(iv) The momentum of a photon is 5.0 x 10-²⁹ kg. m/s. Ignoring relativistic effects (if any), the wavelength of the photon is
(A) 1.33 µm (B) 3.3 µm
(C) 16.6 µm (D) 13.3 µm
Question No. 30- cbse 2025 physics class 12
| solution by ujwal Kumar physics master | physics master academy is best coaching for all physics students.
best physics teacher of neet, JEE-Mains in delhi
Download our app for android and ios on-app.in/app/home?orgCode=vdtxq
