A 60 W bulb is used for 5 hours daily. How much electrical energy is consumed by the bulb in 30 days?
A. 90 kWh
B. 900 kWh
C. 0.9 kWh
D. 9 kWh
Answer: Option D
Solution (By JKSSB Mock Tests)
Electrical energy (E) = Power (P) × Time (t). Power = 60 W = 0.06 kW. Time per day = 5 hours. Total time in 30 days = 5 × 30 = 150 hours. Energy = 0.06 kW × 150 h = 9 kWh (or 9 units of electricity). One kWh is the commercial unit of energy.
Explanation:
Velocity v = fλ constant for given medium. Ultrasound has higher frequency (>20 kHz) than audible sound, so wavelength λ = v/f is smaller. Typical ultrasound in MHz range, λ in mm.
No comments yet. Be the first to start the discussion!