3. An electron moves with speed 2 x 10 ms along
the positive x-direction in the presence of a magnetic
induction B=i+4i-3k tesla. The magnitude of the
force experienced by the electron in newton is
(charge on the electron = 1.6 x 10-19C)
1) 1.18 X 10-13
2) 1.28 x 10-13
3) 1.6 X 10-13
4) 1.72 X 10-13
Answers
Answer:
answer is 1.18×10-13 answer
When a resistance R is connected in parallel to the voltmeter, the effective resistance decreases.
Thereby ammeter reading increases and voltmeter reading decreases.
2. Two long parallel copper wires carry currents of 5A each in the opposite direction . If the wires
are seperated by a distance of 0.5 m, then the force between the two wires is (2000 E)
1) 10-5 N attractive 2) 10-5 N repulsive 3) 2x10-6 N attractive 4) 2x10-5 N repulsive
Ans: 2
Sol. Force between two parallel straight current carrying conductors will be
0 12 i i F .
2 d
µ = π
A
( )( )( ) 7
5 F 2 10 5 5
10 N / m
0.5
−
− ×
⇒= =
A
As the directions of currents are opposite to each other force of repulsion between them is 10–5 N
3 An electron moves with a speed 2 x 105
m/s along the positive x-direction in the presence of a
magnetic induction B =+ − ( 4 3) i j kT . The magnitude of the force experienced by the electron
in newton is (charge on the electron = 1.6x10-19C) (2001 E)
1) 1.18x10-13 2) 1.28x10-13 3) 1.6x10-13 4) 1.72x10-13
Ans: 3
Sol. F = qV × B
( ) ˆˆˆ = ×+ − qVi i 4j 3k
( ) ˆ ˆ = + qV 4k 3j
2 2
19 5
13
F qV 4 3 5qV
5 1.6 10 2 10
1.6 10 N
−
−
= +=
=× × ××
= ×