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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 choke is preferred to a resistance for limiting current in AC circuit because
- A solenoid has length 0.4 cm, radius 1 cm and 400 turns of wire. If a current
- A leaf which contains only green pigments is illuminated by a laser light
- The current flowing through a lamp marked as 50 W and 250 V is
- A block of mass 0.50 kg is moving with a speed of 2.00 ms⁻¹ on a smooth surface.
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….