A certain 20-A circuit breaker trips when the current in it equals 20 A. What is the maximum number of 100-W light bulbs you can connect in parallel in an ideal 120-V dc circuit without tripping this circuit breaker

28

Explanation:

Given

Circuit breaker current is

Power of the light bulb is

Voltage of the DC-circuit is

If the resistance are connected in parallel, they must have same voltage i.e. 120 V

So, Resistance is given by

For the 20 A current and 120 V battery, net resistance is

Suppose there are n resistance in the circuit connected in parallel.

Thus, there can maximum of 28 bulbs.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27