Solved 2024 Sample Question Paper CBSE Class 10 Science — Question 7

(i) Joules law of heating states that the heat dissipated across a resistor is directly proportional to

1. the square of the current flowing through it
2. resistance of the conductor
3. duration of flow of current

i.e., H = I²Rt

(ii) Resistance of conductor depends on —

1. length of the conductor — the resistance of a conductor is directly proportional to the length of the conductor.
   R ∝ l
2. area of cross section — the resistance of a conductor is inversely proportional to it's area of cross section (a) normal to the direction of flow of current.
   R ∝ $\dfrac{1}{a}$
3. temperature of the conductor — the resistance of conductor increases with an increase in it's temperature.
4. nature of material.