As we know resistor is a device that consumed electrical power and convert it into heat. Resistor can be used as a voltage divider in a circuit. There are different connection for resistor, they are series connection, parallel connection and series parallel connection. Here we are going to discuss about " what is the potential difference across the 10 ω resistor? " i.e. potential difference (p.d.) across the load or resistor. It will help you to learn how to calculate p.d. across the resistor.

What is the potential difference across the 10 ω resistor ?

From question, we must need to know that " ω " means omega which is the symbol of ohms i.e. for lower case we write " ω " and for upper case, we write " Ω ". Both are same and represent same quantity i.e. ohms so we can use any of this. Generally, we use ohms (Ω). We will calculate the potential difference across the 10 ω resistor for different cases. 

Case 1 : - what is the potential difference across the 10 ω resistor? for single resistor in a circuit

For this, we need to use ohm's law which is very easy to use. 

From Ohm's law, V = IR

From figure, V = 5 V

For single resistance in a circuit, we don't need to calculate p.d. It is equal to to the source or battery terminal voltage. so 

For question, what is the potential difference across the 10 ohm resistor? The answer is 5 V.

Case 2 : - what is the potential difference across the 10 ω resistor? for 2 resistors in serial connection in a circuit 

Here 15 v is used as a source and two resistors of 5  ohms and 10 ohms are connected in series. We can solve this by using different method.

Method 1 : -

Total resistance = 5 +10 = 15 ohms

Total current ( I ) = V / R = 15 / 15 = 1 A

By using current, potential difference across 10 ohms = 1 x 10 = 10 V

Method 2 : -

Potential difference across 10 ohms = ( R1 x V) / (R1 + R2)

= (10 x 15) / ( 5 + 10)

This method is voltage division method where voltage is divided by using resistor according to its resistance value.

Method 3 : - This method is also simple just you need to take ratio.

Resistance ratio = first resistance : second resistance : third resistance : ..... = R1 : R2 : R3 :....

Here there is only 2 resistance,

 Ratio = R1 : R2

 = 5 : 10

 = 1 : 2

 So divide total voltage ( 15 V ) into 3 i.e. 1 + 2 = 3 parts and 2 of them is 10 ohms resistor so,

 Division voltage = 15 / 3 = 5 V

 P.d. across 10 ohms = 5 x 2 = 10 V

Case 3 : - what is the potential difference across the 10 ω resistor? for 2 resistors in parallel connection a circuit 

Here voltage source is given by 10 V, two resistors of 10 ohms and 20 ohms are connected in parallel. It is very easy for parallel circuit because voltage is constant for parallel circuit. So p.d. across 10 ohms = 10 V