1
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
Change Language
Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is
A
4 $$ \times $$ 1015 Hz
B
5 $$ \times $$ 1015 Hz
C
1.6 $$ \times $$ 1015 Hz
D
2.5 $$ \times $$ 1015 Hz
2
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
Change Language
A 200 W sodium street lamp emits yellow light of wavelength 0.6 $$\mu $$m. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
A
1.5 $$ \times $$ 1020
B
6 $$ \times $$ 1018
C
62 $$ \times $$ 1020
D
3 $$ \times $$ 1019
3
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
Change Language
An electric dipole of moment p is placed in an electric field of intensity E. The dipole acquires a position such that the axis of the dipole makes an angle $$\theta $$ with the direction of the field. Assuming that the potential energy of the dipole to be zero when $$\theta $$ = 90o, the torque and the potential energy of the dipole will respectively be
A
pEsin$$\theta $$,  $$-$$pEcos$$\theta $$
B
pEsin$$\theta $$,  $$-$$2pEcos$$\theta $$
C
pEsin$$\theta $$, 2pEcos$$\theta $$
D
pEcos$$\theta $$,  $$-$$pEsin$$\theta $$
4
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
Change Language
When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as a plane sheet of glass. This implies that the liquid must have refractive index
A
equal to that of glass
B
less than one
C
greater than that of glass
D
less than that of glass