Page 4 - English Class X_cbse new (FINAL).cdr

S. Solution Marking S. Solution Marking
No. Scheme No. Scheme

2. F = 1 q1q2 [1] 4. (i) Nuclear forces are the strongest forces in nature. 1
4πε0 r2  2
(ii) Nuclear forces are independent of charge.
1
( )( )= 9 × 109 ×  2
2 × 10−7 3 × 10−7
[1]
(0.30)2

= 6 × 10−3N

[2] [1]
[1]
3. The following graph shows the variation of coulomb force (F) versus 5. Let q1 = q,q2 = -4q and q3 = +2q and r = 10 cm = 0.10 m
r. [1]
Total work done = [1]
r → r0. [1]
Y 1 q1q2 + 1 q2q3 + 1 q3q1 [1]
4π ∈0 r 4π ∈0 r 4π ∈0 r
[5]
( )= 1

4π ∈0 r
q1q2 + q2q3 + q3q1

r q2(2μC, -3μC) [2]
F
= 1 r (q)(−4q) + (−4q)(+2q) + (+2q)(q)
q1(1μC, 2μC) 4π ∈0

( )= 1 1
4π ∈0 r −4q2 − 8q2 + 2q2  = 4π ∈0 r −10q2

OX ( )= 9 × 109 × −10 1.6 × 10−10 2 = −9 × 109 × 10 × 2.56 × 10−20 × 100
r 0.10 10

= −23.04 × 10−9 = −2.304 × 10−8 J

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