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An isolated sphere has a capacitance of 50pF. What would be the radius of the sphere?
Options
(a) 90cm
(b) 45cm
(c) 11.50cm
(d) 5.75cm
Correct Answer:
45cm
Explanation:
As potential of spherical charge (Q) having radius r is given by V = (1 / 4πε₀) (Q / r)
Also, capacitance, C = Q / V = Q / { (1 / 4πε₀) (Q / r)} C = 4πε₀r
If C = 50 × 10⁻¹² F, then
Radius of the sphere r = 50 × 10⁻¹² / 4πε₀
= 50 × 10⁻¹² × 9 × 10⁹
= 50 × 9 × 10⁻³
= 450 × 10⁻³ m
= 0.450 m = 45 cm
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Topics: Electrostatics
(146)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A radioactive substance emits n beta particles in the first 2 s and 0.5 n beta
- 300j work is done in sliding a 2kg block up an inclined plane of height 10m
- Three fourth of the active material decays in a radioactive sample in 3/4 sec
- The drift speed of electrons in copper wire of diameter and length l is v.
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Topics: Electrostatics (146)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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As Capacitance of Isolated sphere =4π€R
Given,
C=50picofarad
Then,
50×10(power -12)= 1/9×10(power9)×R
R=0.45m or 45cm….