Units in Electricity

Basic Units

• The Base unit of electrical current is the Ampere (A). It measures the amount of electric charge that flows per second.
• The base unit of electrical potential difference and electromotive force is the Volt (V). It quantifies the energy transferred per unit charge.
• Electrical charge itself is measured in Coulombs (C).
• Resistance, which impedes the flow of current, is measured in Ohms (Ω).

Derived and Supplementary Units

• The rate of energy transfer or work done is measured in Watts (W), where 1 Watt equals 1 Joule per second.
• The Joule (J) is a unit of energy, work or quantity of heat.
• Frequency, the rate at which something occurs or is repeated over a particular period of time, is measured in Hertz (Hz). In electrical terms, it commonly refers to the frequency of alternating current or electromagnetic waves.

Non-SI Units

• A milliampere (mA) is a unit of electrical current equal to one thousandth of an ampere.
• A kilovolt (kV) equals a thousand volts. Usually used for high voltages like those seen in power lines.
• A millivolt (mV) is one thousandth of a volt, commonly used in electronics.

Remember: Understanding these units and how they relate to each other is integral for calculations and problem-solving tasks involving electricity. Also, be able to convert between different magnitudes of the same unit (for example, from mA to A or from kV to V).

Numerical Conversions

• 1 kilo (k) equals 1,000 (Example: 1 kV = 1,000 V)
• 1 milli (m) equals 0.001 (Example: 1 mA = 0.001 A)
• 1 micro (μ) equals 0.000001 (Example: 1 μA = 0.000001 A)

Remember: It’s essential to understand and master these conversions, as they come up frequently in examinations and practical work. Always double-check your units when solving electrical problems!