15 a
1. By emission of which of the following element remains unchanged
a) β^- decay b) γ decay
2. Two lens of power –15D and +5D are placed is contact co-axially. The focal length of equlvalent lens is
(A) –10 cm (B) –20 cm (C) +10 cm (D) none
3. The work done in rotating an electric dipole in an electric field is
(A) W = ME (1 – cos θ)(B) W = ME tan θ) (C) W = ME sec θ (D) None
4. If spere of bad conductor is given charge then it is distributed on–
a) outer surface b) inner and outer surface c) only inner surface d)none
5.(Refractive index of water and glasses are4/3and5/3. A light ray is going fromglass to water. Then its critical angle will be
a) Sin^-1 4/5 b) sin^-1 5/4
6. Some of the important communicaiton channels are
a) air b) trasmission lines c) free space d) all
7. A signal is a place of information, which at a particular time has
a) Single value b) Max value c) min value d) two values
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8 Answers
11-a
2-a
3-a
4-d (charge remains localised)
5-a (but it must be from glass to water)
6-d
12. a
Q5. Critical angle in this particular case will not be defined as the ray travels from a rarer medium (water) to a denser one glass (glass).
But if the question implies 'c' for the pair of media thn answer should be A.
1i agree with debashree.
even i was wrong earlier too sorry,2 shud b a.
power of combination=-10 D
=>combination will act as diverging lens=>f is negative
P=1/f
=>f=1/10 metre
=10 cm.
thus f= -10 cm
1sory chinkoos i made an error in ques 2...please check it out now.