Thread: questions in physics help

1 – What is the relation between the main current which flows from the source and the current in each resistor in series ?
The current is same for each resistor in series

2 – What is the relation between the potential difference across the source and the potential differences across each resistor in series ? Which resistor has the highest pd across it ?
potential difference will divide for each resistor in series
the highest pd highest. .. which has lees are


3- A potential difference of 12 V is found to produce a current of 0.40 A in a 3.2 cm length of wire with a uniform radius of 0.40 cm what is the resistance and resistively of wire ?R= V/I
= 12 / 0.40 = 30 Ω

4 – A 3Ω resistor a 6 Ω resistor and 9 Ω resistor are connected in series with a 12 V battery .
Draw a circuit diagram . What are A ) the equivalent resistance
b) the current in each resistor
c ) the pd across each resistor


A) R = R1 + R2 + R3
18 Ω

B ) I = V/R = 18/12 =1.5 A

C ) V= IR
= 1.5 X 18 == 27

Originally Posted by r-soy

1 – What is the relation between the main current which flows from the source and the current in each resistor in series ?
The current is same for each resistor in series

2 – What is the relation between the potential difference across the source and the potential differences across each resistor in series ? Which resistor has the highest pd across it ?
potential difference will divide for each resistor in series
the highest pd highest. .. which has lees are

Since the current is the same through each resistor we have for the th resistor (from Ohm'd law):



that is the potential drop across each is proportional to its' resistance.

CB

Originally Posted by r-soy

3- A potential difference of 12 V is found to produce a current of 0.40 A in a 3.2 cm length of wire with a uniform radius of 0.40 cm what is the resistance and resistively of wire ?R= V/I
= 12 / 0.40 = 30 Ω

You are also asked for the resistivity, which in this case is:



where is the crossectional area of the wire and is its' length.

CB

Originally Posted by r-soy

4 – A 3Ω resistor a 6 Ω resistor and 9 Ω resistor are connected in series with a 12 V battery .
Draw a circuit diagram . What are A ) the equivalent resistance
b) the current in each resistor
c ) the pd across each resistor


A) R = R1 + R2 + R3
18 Ω

B ) I = V/R = 18/12 =1.5 A

C ) V= IR
= 1.5 X 18 == 27

A and B are OK, but C asks for the voltage drop across each resistor, so there are three voltages required, and the answer to (2) tells you their ratios and 4A their sum

CB