1
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length. its new resistance will be
A
$${R \over n}$$
B
n2R
C
$${R \over {{n^2}}}$$
D
nR
2
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
A 250-turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 $$\mu $$A and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180o against the torque is
A
4.55 $$\mu $$J
B
2.3 $$\mu $$J
C
1.15 $$\mu $$J
D
9.1 $$\mu $$J
3
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current $$'I'$$ along the same direction as shown in fogure. Magnitude of force per unit length on the middle wire $$'B'$$ is given by

NEET 2017 Physics - Moving Charges and Magnetism Question 78 English
A
$${{2{\mu _0}{I^2}} \over {\pi d}}$$
B
$${{\sqrt 2 {\mu _0}{I^2}} \over {\pi d}}$$
C
$${{{\mu _0}{I^2}} \over {\sqrt 2 \pi d}}$$
D
$${{{\mu _0}{I^2}} \over {2\pi d}}$$
4
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
The ratio of resolving powers of an optical microscope for two wavelength $$\lambda $$1 = 4000 $$\mathop A\limits^ \circ $$ and $${\lambda _2}$$ = 6000 $$\mathop A\limits^ \circ $$ is
A
9 : 4
B
3 : 2
C
16 : 81
D
8 : 27