**Guess**** ****Paper – 2009**

**Class – X**

**Subject – Physics**** **

__NUMERICALS ON CURRENT ELECTRICITY__

- Find the work done by an electron to maintain the potential difference of 80V?

- What is the potential difference between the ends of 16Ω resistance, when a current of 1.5A flows through it?

- The potential difference across the the terminals of an electric iron is 240V and the current is 6 A what is the resistance of electric iron?

- If there are 10
^{8}electrons flowing across any cross section of a wire in 4 minutes, what is the current in the wire?

- A copper wire has diameter o.5mm and resistivity 1.6 x 10
^{-8}ohm m what will be the length of this wire to make the resistance of 10 ohms?

- Find the effective resistance of resistors 0.01 ohms and 10
^{7}ohms.in series and parallel

- Two resistors of same materials has been connected in series first and then in parallel. Draw a V – I graph to distinguish these connection.

- Three resistors 3,4,5 ohms are joined in parallel in a circuit. If a current of 150 mA flows through the resistor of 4 ohms, then find the values of the current in mA which will be flowing in other two resistors?

- A wire of length 2cm having resistance R is stretched to have an increase of 100% of original length . Find its new resistance with respect to its original resistance.

- An electric lamp has resistance of 400 ohms. It is connected to a supply of 250V. If the price of electric energy is Rs.1.20 per unit, calculate the cost of lighting the lamp for 20 hours.