Benjamin Franklin began experimenting with electricity during the 18th century - Leaving Cert Physics - Question 11 - 2022

An ammeter, galvanometer, or multimeter is used to measure electric current.

To illustrate a torch circuit, draw a simple circuit diagram. The battery is connected to the light bulb, with a switch in series. Refer to standard circuit symbols for accurate representation.

The wires in a circuit are made of metal because metals are good conductors of electricity due to the presence of free-moving electrons that facilitate the flow of charge.

The charge carrier in a metal is an electron.

To calculate the current (I), use the formula: $I = \frac{Q}{t}$ where Q is the charge and t is the time. Substituting the values, we have: $I = \frac{30 \text{ C}}{6 \text{ s}} = 5 \text{ A}$

To find the potential difference (V), use Ohm's Law: $V = I \times R$ where I is the current and R is the resistance. Here: $V = 5 \text{ A} \times 3 \text{ Ω} = 15 \text{ V}$

The formula for total resistance (R_total) in parallel is: $\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2}$. Substituting the values: $\frac{1}{R_{total}} = \frac{1}{3} + \frac{1}{2} = \frac{2}{6} + \frac{3}{6} = \frac{5}{6}$ Hence, $R_{total} = \frac{6}{5} = 1.2 \text{ Ω}$

The resistance of a wire is proportional to its length. Therefore, if a 1.5 m wire has a resistance of 12 Ω, a 3 m piece would have: $R = 2 \times 12 \text{ Ω} = 24 \text{ Ω}$.

The resistance of a wire is inversely proportional to its cross-sectional area. This means that as the cross-sectional area increases, the resistance decreases, and vice versa.