Explanation:
Let R
1
and R
2
be the resistances of the two wires connected in series and parallel respectively.
R
s
= R
1
+ R
2
= 50Ω; ------------ (1)
And, R
p
= R
1
|| R
2
= [(R
1
* R
2
)/(R
1
+ R
2
)] = 80Ω --------------- (2)
From equation 1 R
2
= 50 - R
1
----------- (3)
Putting equation 3 in 2 we get
[(R
1
* (50 - R
1
)/(R
1
+ (50 - R
1
))] = 8
Or R
1
= 10Ω
Putting the value of R
1
in equation 3 we get
R
2
= 40Ω
Therefore, A is the correct answer option.
Question 13
A beam of electrons enters normally in a region of magnetic field of 0.01 T with a velocity of
10
6
m/s. What is the radius of the curved path traced by the beam of electrons? (Charge on
electron = 1.6 x 10
-19
C)
A. 4.5 x 10
-4
m
B. 3.6 x 10
-4
m
C. 5.7 x 10
-4
m
D. 2.8 x 10
-4
m
E. Cannot be determined
Correct Answer: C
Explanation:
If a charged particle enters a region of magnetic field, it experiences a force due to which the charged
particles follow a curved path. The radius of the curved path is given as
r = (mv)/(qB) ------------- (1)
Putting the values in equation 1 we get
r = [(9.1 x 10
-31
x 10
6
) / (1.6 x 10
-19
* 0.01)]
r = 5.7 x 10
-4
m
Therefore, C is the correct answer option.
