Homework Help: Physics

Posted by Tiffini on Sunday, November 14, 2010 at 11:53pm.

3. You have a simple circuit with a light bulb (R = 50 Ω) and a power supply (you can treat it like a battery with 120 V). Unfortunately, a loose screw fell on the circuit and is connected in parallel to the light bulb. You can treat the screw as a resistor with a resistance of 1 Ω.
a. Sketch this circuit

b. What effect does the screw have on the circuit? Focus on the current and voltage.

c. This situation is also known as a “short circuit.” Why is this bad if it happens at home?

Physics - Henry, Wednesday, November 17, 2010 at 8:40pm
a. If the 12ov supply holds up, you have a parallel circuit with a 1 ohm and a 50 ohm resistor in parallel.

b. The current drawn by the lamp:
I = V / R = 120 / 50 = 2.4 Amps.

The current drawn by the 1 ohm resistor:

I = V / R = 120 / I = 120 Amps.

The total current:
I(tot) = 2.4 + 120 = 122.4 Amps.

These calculations were based on the assumption that the 120v supply remained constant This is unlikely
unless the current rating of the power supply is well over 120 Amps. A 1 ohm
resistor connected across a 120v 5 Amp
supply would definitely be a short circuit. But if it is connected across a 120v 100 Amp supply; it would be an overload but not a short circuit.

c. A short circuit can trip a circuit breaker, blow a fuse, or burn the house down.

Answer this Question

Related Questions

physics - A light bulb is wired in series with a 133-Ω resistor, and ...
physics - You are in the lab with a 10 V battery. You have a 10 W light bulb and...
college physics - You are in the lab with a 10 V battery. You have a 10 W light ...
College Physics - The power dissipated by a light bulb increases by 50 W when ...
electrical circuit - When a second light bulb is wired into an electric circuit ...
physics 102 - three lamps connected to a 120-V AC (rms) household supply ...
Physics - Three resistors (14.4 Ω, 21.7 Ω, 14.1 Ω) ...
physics - 010 (part 1 of 5) 10.0 points A string of 26 identical Christmas tree ...
science - i have a picture of a battery a light bulb and a wire. i know to light...
Physical Science - 1.Nico uses wire to connect a battery, light bulb, and a ...

For Further Reading

First Name:
School Subject:
Answer: