1
AIPMT 2008
MCQ (Single Correct Answer)
+4
-1
In an a.c. circuit the e.m.f. ($$\varepsilon $$) and the current

(i)  at any instant are given respectively by
$$\varepsilon $$ = E0sin$$\omega $$t,   $$i$$ = $$I$$0sin($$\omega $$t $$-$$ $$\phi $$)

The average power in the circuit over one cycle of a.c. is
A
$${{{E_0}{I_0}} \over 2}\cos \phi $$
B
$${{E_0}{I_0}}$$
C
$${{{E_0}{I_0}} \over 2}$$
D
$${{{E_0}{I_0}} \over 2}\sin \phi $$
2
AIPMT 2008
MCQ (Single Correct Answer)
+4
-1
The velocity of electromagnetic radiation in a medium of permittivity $$\varepsilon $$0 and permeability $$\mu $$0 is given by
A
$${1 \over {\sqrt {{\mu _0}{\varepsilon _0}} }}$$
B
$$\sqrt {{{{\mu _0}} \over {{\varepsilon _0}}}} $$
C
$$\sqrt {{{{\varepsilon _0}} \over {{\mu _0}}}} $$
D
$$\sqrt {{\mu _0}{\varepsilon _0}} $$
3
AIPMT 2008
MCQ (Single Correct Answer)
+4
-1
A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively
A
both remain the same
B
1.1 times, 1.1 times
C
1.2 times, 1.1 times
D
1.21 times, same
4
AIPMT 2008
MCQ (Single Correct Answer)
+4
-1
A boy is trying to start a fire by focusing sunlight on a piece of paper using an equiconvex lens of focal length 10 cm. The diameter of the sun is 1.39 $$ \times $$ 109 m and its mean distance from the earth is 1.5 $$ \times $$ 1011 m. What is the diameter of the sun's image on the paper ?
A
6.5 $$ \times $$10$$-$$5 m
B
12.4 $$ \times $$10$$-$$4 m
C
9.2 $$ \times $$10$$-$$4 m
D
6.5 $$ \times $$10$$-$$4 m
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