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gtqueen371

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**Three bulbs**

A circuit is made of two 1.5 volt batteries and three light bulbs as shown in Figure 19.57. When the switch is closed and the bulbs are glowing, bulb 1 has a resistance of 9 ohms, bulb 2 has a resistance of 44 ohms, bulb 3 has a resistance of 28 ohms, and the copper connecting wires have negligible resistance. You can also neglect the internal resistance of the batteries.

A circuit is made of two 1.5 volt batteries and three light bulbs as shown in Figure 19.57. When the switch is closed and the bulbs are glowing, bulb 1 has a resistance of 9 ohms, bulb 2 has a resistance of 44 ohms, bulb 3 has a resistance of 28 ohms, and the copper connecting wires have negligible resistance. You can also neglect the internal resistance of the batteries.

Picture Attached of Circuit

**2. (a) With the switch open, indicate the approximate surface charge on the circuit diagram. Which of the following statements about the circuit (with the switch open) are true:**

1. The electric field in the filament of bulb 3 is zero.

2. There is a large gradient of surface charge between locations M and L.

3. The surface charge on the wire at location B is positive.

4. The electric field in the air between locations B and C is zero.

5. There is no excess charge on the surface of the wire at location C.

1. The electric field in the filament of bulb 3 is zero.

2. There is a large gradient of surface charge between locations M and L.

3. The surface charge on the wire at location B is positive.

4. The electric field in the air between locations B and C is zero.

5. There is no excess charge on the surface of the wire at location C.

I chose 2, 3, and 4. This is not the correct combination of answers. 1 should be wrong because there is current flowing through the filament, E can't be xero in the bulb. I figured 2 was correct because the wire would have a large negative gradient as current leaves the negative end of the battery. I thought 3 would be correct due to it being on the side of the circuit closest to the + end of the battery, and I picked 4 because I thought the charges on either side of the switch would cancel each other out. There is a negative excess surface charge at C, so 5 is incorrect.

**(b) With the switch open, find these potential differences:**

1. V

2. V

1. V

_{B}- V_{C }=2. V

_{D}- V_{K}=I thought 1 was 0 because current isn't traveling past the switch since its open, and I assumed 2 was 3 because this the same as the delta V leaving the battery.

**(c) After the switch is closed and the steady state is established, the currents through bulbs 1, 2, and 3 are I1, I2, and I3 respectively. Which of the following equations are correct loop or node equations for this steady state circuit?**

1. I1 = I2 + I3

2. -I1*(9 )-I2*(44 ) + I3*(28 ) = 0

3. -I2*(44 ) + I3*(28 ) = 0

4. + 3V + -I1*(9 ) + -I2*(44 ) = 0

5. I2 = I3

6. +3V + -I1*(9 ) + I3*(9 ) = 0

1. I1 = I2 + I3

2. -I1*(9 )-I2*(44 ) + I3*(28 ) = 0

3. -I2*(44 ) + I3*(28 ) = 0

4. + 3V + -I1*(9 ) + -I2*(44 ) = 0

5. I2 = I3

6. +3V + -I1*(9 ) + I3*(9 ) = 0

I chose 1, 4, and 5. Perhaps I should have also chosen 2?

**(d) In the steady state (switch closed), which of these are correct?**

1. VC - VF = +I1*(9 )

2. VC - VF = +I2*(44 )

3. VC - VF = 0

4. VL - VA = -3V + I1*(9 )

5. VC - VF = +I3*(28 )

1. VC - VF = +I1*(9 )

2. VC - VF = +I2*(44 )

3. VC - VF = 0

4. VL - VA = -3V + I1*(9 )

5. VC - VF = +I3*(28 )

I chose 2 and 4.

**(f) Now find the unknown currents, to the nearest milliampere.**

I1 =

I2 =

I3 =

I1 =

I2 =

I3 =

I doesn't matter what I got here because the calculations were wrong due to earlier mistakes.

**(g) How many electrons leave the battery at location N every second?**

____________electrons/s

____________electrons/s

Incorrect calculation due to earlier assumptions, but i=I/q.

**(i) What is the numerical value of the power delivered by the batteries?**

P = ___________W

P = ___________W

Incorrect calculation due to earlier assumptions, but P=deltaV/R.

**(j) The tungsten filament in the 44 ohm bulb is 10 mm long and has a cross-sectional area of 2 multiplied by 10-10 m2. What is the magnitude of the electric field inside this metal filament?**

|e vector| = ________ V/m

|e vector| = ________ V/m

Incorrect calculation due to earlier assumptions, but E=emf/L.

**I am a first time poster, tyring out this site, and any help will be GREATLY appreciated! :0)**