Having trouble with voltage drop here.

[JAWS]

Hello again.

Finding the power I’ve done, finding the current but for the life of me I’m struggling to find the voltage drop across R1 & R2.



I’m sure I’ve been doing all the calculations correctly but I can’t end up with 10.11v.

It is one of them I’d say once you’ve done it once it will become easier.

Apologies for the questions.

Thank you

 

[Richard Burns]

Total resistance of circuit is calculated and then current is calculated from i=v/r.
Then volt drop over R1R2 is v=IR
Roughly 3.2+8+4.7 gives current 50/16=3.25 multiply by R1R2 resistance of 3.2 gives 10

 

[Jamie']

Doing it on the train without a scientific calculator I got to 10.01o ohms.


1/6 + 1/7 = 1/ans(1)

1/9+1/10 = 1/ans(2)

Ans(1)+ ans(2) + 8 = total ohms

50/Total ohms = A

A x ans(1) = volt drop across r1 R2

 

[DavidSpark]

So on the surface this looks like quite a tricky question but if you break it into steps it's quite a simple process.

As we know, V = IR, so to find any voltage drop we must have resistance and current. As we are given the resistance of individual parts we need to add these together in order to get to the total resistance (Rtotal) of the circuit to find the total current drawn (Is)

 

[Loki]

Doing it on the train without a scientific calculator I got to 10.01o ohms.


1/6 + 1/7 = 1/ans(1)

1/9+1/10 = 1/ans(2)

Ans(1)+ ans(2) + 8 = total ohms

50/Total ohms = A

A x ans(1) = volt drop across r1 R2

My best guess is that your getting 10.01v (volts not ohms) is that you have been reducing your sub answers to say 2 or 3 decimal places. Doing that will throw your answer off a bit.
Do the decimal place bit at the end on the final answer.

1/6+1/7= 0.3095238095
1/0.3095238095= 3.230769231

1/9+1/10= 0.2111111111
1/0.2111111111= 4.7368421055

3.230769231 + 8 + 4.7368421055 = 15.9676113365

50v / 15.9676113365 = 3.1313387423

3.230769231 × 3.1313387423 =
10.1166328605

10.1166328605 to 2 significant figures is
10.11


Michael

 

[telectrix]

should read 10.12 to 2 sig. fig. as the "6" in 10.116 is >5, roundup not down.

 

[Jamie']

My best guess is that your getting 10.01v (volts not ohms) is that you have been reducing your sub answers to say 2 or 3 decimal places. Doing that will throw your answer off a bit.
Do the decimal place bit at the end on the final answer.

1/6+1/7= 0.3095238095
1/0.3095238095= 3.230769231

1/9+1/10= 0.2111111111
1/0.2111111111= 4.7368421055

3.230769231 + 8 + 4.7368421055 = 15.9676113365

50v / 15.9676113365 = 3.1313387423

3.230769231 × 3.1313387423 =
10.1166328605

10.1166328605 to 2 significant figures is
10.11


Michael

Quite right their sir, didn't have the privilege of a scientific calculator on the train to work this morning so just done it roughly to give some guidance.

 

[JAWS]

Thank you very much fellas I’m pleased I done all the working outs correctly but for someone reason I never X the 3.320 by 3.131.

Really appreciate your help.

 

[Loki]

Quite right their sir, didn't have the privilege of a scientific calculator on the train to work this morning so just done it roughly to give some guidance.

No worries to be honest when i replied i hadnt noticed it wasnt massive1 & had assumed it was