Electrical Circuit Question. The 3 bulbs at different brightness.

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This is a circuit i tried recently . I have recorded my observation below and i need to know why it happens like that?
230 V
______________(~)_____________
| |
| |
| |
| 62V 130V 38V |
| __(v)__ __(v)__ __(v)___ |
| | | | | | | |
| | | | | | | |
|_|__(x)__|___|__(x)__|___|__(x)__|_|
A B C
60W 40W 100W

Key: (x) = Bulb

(v) = voltmeter

(~) = AC Voltage

I have connected 3 Tungsten Bulbs to an AC source of 230 voltage in series. Each glows differently.
Bulb A is 60Watts, B is 40Watts, C is 100Watts.
I noticed that Bulb B is the Brightest, Bulb A is dim and Bulb C is the dimmest. (least bright). I recorded the voltage across each using a multimeter and indicated in the diagram.
The voltages measured may be up or down by 2 to 3 volts due to practical errors.

Normally the 100 W is always the brightest when compared with other bulbs in a single circuit i.e bulb is connected alone to the power source.
Q1) Why does the 40 W bulb glow the brightest?
Q2) Why is the voltmeter showing the highest reading across the 40 W bulb B?
Q3) What is the resistance in each case?
Q4) What is the current drawn ? is it different in each bulb or same .
Q5) What is the Power in each?
Q6) What is the Energy used each?

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@emmfranklin,

This is the kind of exercise you get in electricity classes.

So, I guess it's your homework.

Using the two formulas you learned, do your work:

P=VI
and
V=IR

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@emmfranklin,

- Use P = V^2/R to solve the for the resistance value for each bulb.
- Since the bulbs are in series, they each see the same current. Use V = IR to compute the current where R is the sum of the resistances above.
- Use P = IR for each bulb to compute the power consumed at each bulb.

Do that and you should be able to answer all six questions.

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@engineer,

Quote:

Use P = IR for each bulb to compute the power consumed at each bulb.

P = I^2 * R

NOT P =IR

1 Reply

@emmfranklin,

Q1) Why does the 40 W bulb glow the brightest?

Having the highest resistance, Frank, it gets a bigger share of the available voltage

Q2) Why is the voltmeter showing the highest reading across the 40 W bulb B?

See Ql above

Q3) What is the resistance in each case?
Q5) What is the Power in each?

See other replies

Q4) What is the current drawn ? is it different in each bulb or same .

In series, current same

Q6) What is the Energy used each?

What sort of energy

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@Ragman,

Thanks.

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Electrical Circuit Question. The 3 bulbs at different brightness.

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