You are Here: Home >< A-levels

# Physics Electricity help Watch

1. I suck at everything to do with electricity apparently..
question:
Three identical resistors are connected across a potential difference V so that one of them is in
parallel with the other two which are connected in series. The power dissipated through the first
one, compared to the power dissipated by each of the other two, is approximately
A the same
B half as much
C twice as much
D four times as much

I thought the answer was A... :/ Help pls... can you explain the concept too please thanks. Also is this part of the new a-level spec or nah?
2. bump
I suck at everything to do with electricity apparently..
question:
Three identical resistors are connected across a potential difference V so that one of them is in
parallel with the other two which are connected in series. The power dissipated through the first
one, compared to the power dissipated by each of the other two, is approximately
A the same
B half as much
C twice as much
D four times as much

I thought the answer was A... :/ Help pls... can you explain the concept too please thanks. Also is this part of the new a-level spec or nah?
Well what can you say about the voltages in each branch, and how could we use this
4. (Original post by samb1234)
Well what can you say about the voltages in each branch, and how could we use this
Voltage is the same in the parallel part right? It's split between components in series?
Voltage is the same in the parallel part right? It's split between components in series?
So what is the voltage across one of the resistors in the branch with 2 resistors compared to the resistor in the other branch, and how can we relate this to power
6. Voltage will be... Split... so you'll have half in one resistor and half in the other... So if you had a voltage of 12V... you'd get 6V in one resistor nd 6V in the other. Assume Resistors are all 1 ohm...
P=V^2/R
so You'd get P = 36/1 = 36

In the parallel one you'd get... 12V
Then P=V^2/R
P = 144/1 = 144.

144/36...
OKAY i got it.. THANKS DUDE. =) Answer is D... Thanks a bunch

(Original post by samb1234)
So what is the voltage across one of the resistors in the branch with 2 resistors compared to the resistor in the other branch, and how can we relate this to power
Voltage will be... Split... so you'll have half in one resistor and half in the other... So if you had a voltage of 12V... you'd get 6V in one resistor nd 6V in the other. Assume Resistors are all 1 ohm...
P=V^2/R
so You'd get P = 36/1 = 36

In the parallel one you'd get... 12V
Then P=V^2/R
P = 144/1 = 144.

144/36...
OKAY i got it.. THANKS DUDE. =) Answer is D... Thanks a bunch
No problem, you could also have done it algebraically but plugging in numbers works too (i normally would do algebra first then plug some numbers into check) - voltage is double so since p is proportional to v^2 if voltage doubles power quadruples

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 2, 2016
Today on TSR

### Medicine offers rolling in

Which unis have sent theirs?

### I refused to be served by tattooed cashier

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll

## All the essentials

### Student life: what to expect

What it's really like going to uni

### Essay expert

Learn to write like a pro with our ultimate essay guide.

### Create a study plan

Get your head around what you need to do and when with the study planner tool.

### Resources by subject

Everything from mind maps to class notes.

### Study tips from A* students

Students who got top grades in their A-levels share their secrets

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.