Chapter 13: Current Electricity

This is a thirteenth chapter of the book Physics 12 published by Punjab Curriculum and Textbook Board, Lahore, Pakistan.

After studying this chapter, the students will be able to:

• Understand the concept of steady current.
• Describe some sources of current.
• Recognize effects of current.
• Understand and describe Ohm's law.
• Sketch and explain the current-voltage characteristics of a metallic conductor at constant temperature, diode and filament lamp.
• Understand resistivity and explain its dependence temperature.
• Understand and and elaborate conductance and conductivity of conductor.
• Solve problems relating the variation of resistance with temperature for one dimension current flow.
• Know the value of resistance by reading co-lour code on it.
• Know the working and use of rheostat in the potential divider circuit.
• Describe the characteristic the of thermistor.
• Use the energy considerations to distinguish between emf and p.d.
• Understand the internal resistance of sources and its consequence for external circuits.
• Describe the conditions for maximum power transfer.
• Know and use the application of Kirchhoff's first law conservation of charge.
• Know and use the application of Kirchhoff's second law as conservation of energy.
• Describe the function of Wheatstone Bridge to measure the unknown resistance.
• Describe the function of potentiometer to measure and compare potential without drawing any current from the circuit.