1. Simple circuit Connect the solar cell to a resistance. ▫ Measure the resistance and current. ▫ Repeat for different resistors. ▫ Can you find the relationship between voltage, current and resistance? 1

2. Ohm’s Law and Current Measurement Connect 1.5V battery to the two resistors connected in series. a) Measure the voltage across each resistor. b) Calculate the current in the circuit using Ohm’s law and verify experimentally Connect 1.5V battery to the two resistors connected in parallel. a) Measure the voltage across each resistor. b) Calculate the current in the circuit, through each resistor using Ohm’s law and verify experimentally. 2

3. Home assignment Take a look at your KUB bill. What are we charged for? power or energy used? What do you think is the unit cost of electricity we pay? How are appliances rated- power or energy? Please list the rating of atleast two electric appliances. 3

4. Short Circuit and Open circuit In an open circuit, no current flows. A short circuit exists whenever the resistance of a circuit or the resistance of a part of a circuit drops in value to almost zero ohms.( R~=0) This causes an infinite (huge) current!!! Closed circuit is one where there is a finite amount of current flow. 4

5. ApplianceWatts Computer20-75 Desktop PC80-200 Bulbs (incandescent)40-100 Compact Fluoroscent Lamps(CFL)11-23 Microwave600-1500 Refrigerator( 20cf)540 Air conditioner( central/ room)2000-5000 /1000 Fan(ceiling)10-50 Dishwasher1500 Washing machine/dryer500/ 4000 toaster800-1500 5