Structure of atom - The ultimate source of charge

Type of Charge

Property of Charge

Why do electrons flow?

Why do electrons only flow in metals and not in non metals?

Structure of atom - The ultimate source of charge

Type of Charge

Property of Charge

Why do electrons flow?

Why do electrons only flow in metals and not in non metals?

Static Charge

SI unit of Charge

Electricity - Moving charge 

SI unit of current

What is Potential Difference.

Drawing parallel from real life observation

Formula for Potential Difference

SI unit of potential difference

Examples

1. What does an electric circuit mean?
2. Define the unit of current.
3. Calculate the number of electrons constituting one coulomb of charge

1. Name a device that helps to maintain a potential difference across a conductor.
2. What is meant by saying that the potential difference between two points is 1 V?
3. How much energy is given to each coulomb of charge passing through a 6 V battery?

1. On what factors does the resistance of a conductor depend?

2. Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?

3. Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?

4. Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal

1. Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 Ωresistor, an 8 Ωresistor, and a 12 Ωresistor, and a plug key, all connected in series.

2. Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 Ωresistor. What would be the readings in the ammeter and the voltmeter?

1. Judge the equivalent resistance when the following are connected in parallel – (a) 1 Ω and 10 ^6 Ω,(b) 1 Ωand 10^3 Ω, and 10^6 Ω.

2. An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter  of resistance 500 Ωare connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances, and what is the current through it?
3. What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?
4. How can three resistors of resistances 2 Ω, 3 Ω, and 6 Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω?
5. What is (a) the highest, (b) the lowest total resistance that can be secured  by combinations of four coils of resistance 4 Ω, 8 Ω, 12 Ω, 24 Ω?

1. Why does the cord of an electric heater not glow while the heating element does?

2. Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.

3. An electric iron of resistance 20 Ωtakes a current of 5 A. Calculate the heat developed in 30 s

1. What determines the rate at which energy is delivered by a current?

2. An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h.

18. Explain the following.

(a) Why is the tungsten used almost exclusively for filament of electric lamps? (b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal? (c) Why is the series arrangement not used for domestic circuits? (d) How does the resistance of a wire vary with its area of cross-section? (e) Why are copper and aluminium wires usually employed for electricity transmission?