Saturday, 6 September 2014

OHM'S LAW- PROBLEMS


Ohm's law

1. Calculate the current through the following resistors:
(a) 100 Ω   connected to 240V    (b) 4700 Ω   connected to 24V
(c) 10kΩ   connected to 3V    (d) 2.5MΩ    connected to 30V

2.  What is the resistance of the following?
(a) a torch bulb that draws 0.25 A from a 12V supply
(b) an immersion heater that draws 10 A from a 240V supply 
(c) a watch taking a current of 0.25 mA from a battery of 1.5 V

3. Under what conditions is Ohm's law obeyed?

4. Under what conditions is Ohm's law not obeyed?
5. What voltage is required to give a current :
(a) of 2 A through a resistor of 200 Ω?
(b) of 50 mA through a resistor of 1000 Ω?
(c) of 200 mA through a resistor of 300 kΩ?