Circuit Diagram and Ohm's law

1. Draw the symbols of the following components:
a) An electrical cell
b) A battery or a combination of three cells
c) switch(open)
d) switch (closed)
e) A wire joint
f) Wires crossing without joining
g) Electric bulb
h) A resistor
i) Rheostat
j) Ammeter
k) Voltmeter

Ans: Draw all the symbols from table 12.1 from your text book.

2. Write the Ohm's law. Give its mathematical expression.

Ans: The potential difference, V, across the ends of s given wire in a metallic wire in an electric circuit is directly proportional to the current flowing through it, provided its temperature remains the same. This is called Ohm’s law.

i.e.          V ∝ I

or           V=RI

R is a constant for the given metallic wire at a given temperature and is called resistance.

3. What is resistance? What is its unit?

Ans: Resistance is the property of the conductor to resist the flow of charges through it. Its SI unit is ohm (Ω). According to Ohm’s law,

R=V/I;   V ➡️potential difference

   I➡️ current

4. Define 1 Ω resistance.

Ans: According to Ohm’s law,

R=V/I.

If the potential difference across the two ends of a conductor is 1 V and the current through it is 1 A, then the resistance R, of the conductor is 1 Ω.

i.e. 1 Ω = 1 V/1 A

5. What is rheostat? What is its function?

Ans: Rheostat is a variable resistor.

         It is used to change the resistance in an electric circuit. Hence, using this current can be controlled in the circuit without changing the voltage source.