Which of the following has the lowest internal resistance when new?
A
leclanche cell
B
Daniel cell
C
Accumulator
D
Torch battery
CORRECT OPTION:
c
32
When a biro pen rubbed on a dry silk cloth is moved very close to a piece of paper on a dry table, the pen is found to pick up the paper. This is because
A
both the pen and the cloth are magnetized
B
the pen is magnetized but the cloth is not
C
the pen is charged while the cloth is magnetized
D
both the pen and the cloth are charged
CORRECT OPTION:
d
They are all charged either positively or negatively
33
A capacitor 8\(\mu\)F is charged to a potential difference of 100V. The energy stored by the capacitor is
A
1.0 x 104J
B
8.0 x 10J
C
1.25 x 10J
D
4.0 x 10-2J
CORRECT OPTION:
d
Energy = \(\frac{1}{2}\)CV2
= \(\frac{1}{2}\) x 8 x 10-6 x (100)2
= 4 x 10-2J
34
Two capacitors R1 = 4\(\Omega\) and R2 = 5\(\Omega\) are connected in parallel across a potential difference. If P1 and P2 represent power dissipated in R 1 and R2 respectively, then the ratio P1 : P2 is
A
4 : 5
B
5 : 4
C
16 : 25
D
25 : 16
CORRECT OPTION:
b
P1 = \(\frac{V^2_1}{R_1}\) and P2 = \(\frac{V^2_2}{R_2}\)
P1R1 = P2R2
4P1 = 5P2
\(\frac{p_1}{p_2}\) = \(\frac{5}{4}\)
= 5 : 4
35
Which of the following are found in the receiver but not in the microphone of a telephone handset? i. Diaphragm. ii. soft iron pole pieces. iii. permanent magnet. iv.carbon blocks
A
i and ii
B
i and iv
C
ii and iii
D
iii and iv
CORRECT OPTION:
b
36
If two parallel conductors carry currents flowing in the same direction, the conducts will
A
attract each other
B
repel each other
C
both move in the same direction
D
have no effect on each other
CORRECT OPTION:
a
37
A certain radioisotope of \(^{235}_{92}U\) emits four alpha particles and three beta particles. The mass number and the atomic number of the resulting elements respectively are