Definition and unit of resistance Ohm’s law Resistors in series and parallel Potential divider Resistivity Resistance varies with length, cross-sectional area and temperature Effect of temperature on different types of resistors
Conduction (with reference to charge carriers) in metals, ionic solutions (with either active or inactive electrodes), gases, a vacuum and semiconductors
Wheatstone bridge and metre bridge
MANDATORY EXPERIMENTS: 21. Measurement of the resistivity of the material of a wire 22. Investigation of the variation of the resistance of a metallic conductor with temperature 24. Investigation of the variation of current (I) with voltage (V) for a (a) metallic conductor (b) filament bulb (c) copper sulphate solution with copper electrodes
ACTIVITIES:
Demonstration of a potential divider Interpretation of current-voltage graphs Use of an ohmmeter and a metre bridge
SCIENCE,TECHNOLOGY AND SOCIETY:
Advantage of use of EHT in transmission of electrical energy Potentiometer as a variable potential divider Everyday examples of conduction in gases (neon lamps, street lights) Practical uses of Wheatstone bridge for temperature control and fail-safe device
PHYSICAL QUANTITIES INTRODUCED IN THIS CHAPTER: Quantity
