Answer :
Final answer:
To calculate the lamp's resistance, one uses the power and voltage to find the current, then applies Ohm's Law. For the battery's emf, the terminal potential difference and internal resistance are used with the formula V = emf - Ir.
Explanation:
Understanding Circuit Calculations
To find the resistance of the lamp, we can use the formula
Power (P) = Voltage (V) × Current (I), and Ohm's Law,
which states V = I × R (where R is resistance). We can rearrange Ohm's Law to R = V / I.
The power of the lamp is given as 4.5 W and the working potential difference is 6.2 V,
so the current can be calculated as I = P / V = 4.5 W / 6.2 V. Using this current, we can determine the resistance of the lamp at its working potential difference.
To calculate the emf of the battery, given that the terminal potential difference (pd) across the battery is 6.2 V and the internal resistance is stated as 2 ohms, we use the formula V = emf - Ir,
where I is the current through the internal resistance and V is the terminal pd.
By rearranging the equation to emf = V + Ir,
we can find the emf when I (current through internal resistance) and r (internal resistance) are provided.
