27. Resistors & DC Circuits

Two resistors, $R_1$ and $R_2$, are connected in series to a constant voltage source such that $R_1>R_2$. Which resistor dissipates more power?

An incandescent lightbulb produces 100 W of light. If this lightbulb operates at 25% efficiency (meaning that out of all the power it generates, only 25% is released as light), what resistance must the lightbulb have if it operates at 120 V?

A $30$-watt light bulb is designed to operate at a voltage of $28$ volts. What is the operating resistance of the bulb?

In a circuit, a current of $2.0 A$ flows through a resistor of resistance $5.0 \Omega$. What is the total rate at which electrical energy is dissipated in the $5.0 \Omega$ resistor?

In a $120$-volt circuit, ten identical light bulbs each rated at $60$ watts are connected in parallel. What is the total current (amperage) drawn by the circuit?

Which quantity in a circuit is defined as the amount of work being done per unit of time? $$

A hair dryer operates at 120 V (the voltage produced by a household outlet), and outputs 1200 W of energy. For this problem, treat the hair dryer as a single resistor. 

(a) At what current does the hair dryer operate?
(b) What is the resistance of the hair dryer?