A circuit contains sic 60-W lamps with a resistance of 240-ohm each and a 10.0-ohm heater connected in parallel. The voltage across the circuit is 120 V. Find the current in the circuit for the following situations::::

a. four lamps are turned on
b. all of the lamps are turned on
c. six lamps and the heater are operating.



Physics - drwls, Friday, February 26, 2010 at 8:11am
In each case, add the currents of all of the operating lamps and heater.

For the lamps, the current drawn by each ont that is "on" is I = V/R
= 120/ 240 = 0.5 A

For the heater, the current drawn is 120/10 = 12 A

---- Ok, i understand some of this. For the six lamps turned on is 0.5 A. For the four lamps turned on, would i divide 240/4 = 60 and then find the current.

- Thanks a lot and have a good weekend.

yes, don't forget about the heater, it draws 10 amps when on.

Hey there! I'm here to help with your question. To find the current in the circuit, you need to add up the currents of all the operating lamps and the heater.

Let's break it down:

a. If four lamps are turned on, you're correct that you divide the resistance of a single lamp (240 ohms) by the number of lamps turned on (4). So, the resistance for the four lamps turned on is 240/4 = 60 ohms. Using Ohm's law, you can calculate the current: I = V/R = 120/60 = 2 amps.

b. If all of the lamps are turned on, you have all six lamps operating. The resistance for six lamps is 240/6 = 40 ohms. Using Ohm's law again, you can find the current: I = V/R = 120/40 = 3 amps.

c. For six lamps and the heater operating, you simply add the current drawn by the lamps (3 A) to the current drawn by the heater (12 A). So, the total current in the circuit would be 3 A + 12 A = 15 amps.

I hope this clarifies things for you! If you have any more questions, feel free to ask. Have a great weekend!

No, to find the current when four lamps are turned on, you need to multiply the current drawn by each lamp by the number of lamps turned on.

The current drawn by each lamp is 0.5 A, so when four lamps are turned on, the total current drawn by the lamps would be 0.5 A x 4 = 2 A.

Since the heater is connected in parallel to the lamps, its current remains the same in all scenarios. The current drawn by the heater is 12 A.

To find the total current in the circuit, you need to add the currents drawn by the lamps and the heater.

a. Four lamps turned on:
Total current = Current drawn by lamps + Current drawn by heater
= 2 A + 12 A
= 14 A

b. All lamps turned on:
Total current = Current drawn by lamps + Current drawn by heater
= (0.5 A x 6 lamps) + 12 A
= 3 A + 12 A
= 15 A

c. Six lamps and the heater operating:
Total current = Current drawn by lamps + Current drawn by heater
= (0.5 A x 6 lamps) + 12 A
= 3 A + 12 A
= 15 A

So, in all three scenarios, the total current in the circuit is 14 A when four lamps are turned on, and 15 A when all lamps and the heater are operating.

To find the current in the circuit for each situation, you need to follow the steps mentioned by drwls.

a. Four lamps turned on: Since there are six lamps in total, and only four are turned on, you need to calculate the current drawn by each individual lamp when it is on. The current drawn by each lamp is given by Ohm's Law: I = V/R, where V is the voltage across the circuit (120V) and R is the resistance of each lamp (240 ohms). Therefore, the current drawn by each lamp is I = 120V / 240 ohms = 0.5 A.

b. All of the lamps turned on: In this case, all six lamps are turned on, so you need to find the current drawn by each individual lamp. As mentioned earlier, the current drawn by each lamp when it is on is 0.5 A.

c. Six lamps and the heater operating: In addition to the six lamps, there is also a heater operating. The resistance of the heater is given as 10.0 ohms. To find the current drawn by the heater, use Ohm's Law: I = V / R, where V is the voltage across the circuit (120V) and R is the resistance of the heater (10.0 ohms). Therefore, the current drawn by the heater is I = 120V / 10.0 ohms = 12 A.

Remember to add up the currents drawn by all the operating lamps and the heater in each situation to find the total current in the circuit.