1
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
A concave mirror of focal length $$f$$1 is placed at a distance of d from a convex lens of focal length $$f$$2. A beam of light coming from infinity and falling on this convex lens $$-$$ concave mirror combination returns to infinity. The distance d must equal
A
$${f_1} + {f_2}$$
B
$$-$$$${f_1} + {f_2}$$
C
2$${f_1} + {f_2}$$
D
$$-$$2$${f_1} + {f_2}$$
2
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
The magnifying power of a telescope is 9. When it is adjusted for parallel rays the distance between the objective and eyepiece is 20 cm. The focal length of lenses are
A
10 cm, 10 cm
B
15 cm, 5 cm
C
18 cm, 2 cm
D
11 cm, 9 cm
3
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
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
4
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
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
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