Question

If the energy of a 100 $\pi F$ capacitor charged to 6 kV could all be used to lift a 50 kg mass, hat would be the greatest vertical height through which mass could be raised?

• A. 0.6 mm
• B. 3.6 m
• C. 1.2 mm
• D. 12 m

Answer 1

Answer: (B)

3.6 m

Answer 2

Energy stored in the capacitor is used in lifting the mass. $\therefore$ $mgh=\frac{1}{2}C{{V}^{2}}$ $50\times 9.8\times h=1\times 100\times {{10}^{-6}}\times {{(6\times {{10}^{3}})}^{2}}$ $50\times 9.8\times h=\frac{1}{2}\times 100\times {{10}^{-6}}\times 36\times {{10}^{6}}$ $\therefore$ $h=\frac{1800}{50\times 9.8}=3.6\,m$