A current through a wire depends on time as i = α0t + βt2, where α0 = 20 A/s and β = 8 A/s2. Find the charge crossed through a section of the wire in 15 s.

A room heater is rated 400 W, 220 V. If the supply voltage drops to 200 V, what will be the power consumed (approximately)?

A resistor is connected to a battery of 12 V emf and internal resistance 2 Ω. If the current in the circuit is 0.6 A, the terminal voltage of the battery is: