Page 202 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

Therefore:

ACTIVITY 6000 ÷ 230 = 26 amps (I)
Transposing the Ohm’s Example 3
law formula: Using the Ohm’s law formula, voltage = current × resistance, calculate the

voltage in a circuit that has a resistance of 115 ohms and a current of 2 amps.
Voltage = Current ×
Resistance
The formula for this is:
calculate the resistance in
a circuit that has a voltage V = I × R
of 230 volts and a current Therefore:
of 15 amps.
115 × 2 = 230 volts

Voltage, current and resistance in series
and parallel circuits

Series circuits

A series circuit is one where there is only one path from the source through all
the loads back to the source. This means that the current must flow through
all the loads.

Source 230 volt

Earth wire omitted for clarity

p Figure 3.43 A simple series circuit
In the circuit of light bulbs shown in Figure 3.43, if one of the light bulbs blows,
the whole circuit will become open, the circuit will stop operating and all the
light bulbs will go out. So, how does a series circuit operate?

40 watt

Source 230 volt Switch

Earth wire omitted for clarity
p Figure 3.44 A simple series circuit with one resistor

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