Electrical equipment in an office takes a current of 13 A from a 240 V supply. Estimate the cost per week of electricity if the equipment is used for 30 hours each
week and 1 kWh of energy costs Rm0.50

The cost per week of electricity is Rm 46.8

Explanation:

Electrical Power and Energy

The electrical power consumed by an appliance connected to a voltage V and carrying a current I is given by:

P = V.I

The energy consumed by an electrical appliance of power P during a time t is:

E = P.t

The electrical equipment in an office takes I=13 A when connected to a V=240 V supply.

The power consumed is:

P = 240 V * 13 A

P = 3,120 Watt

Converting to Kilowatt:

P = 3,120/1,000 KW

P = 3,12 KW

If the equipment is used t=30 hours each week, the energy is:

E = 3.12 KW * 30 h

E = 93.6 KWh

Since the cost of each KWh is Rm 0.50, the weekly cost of electricity is:

C = 93.6 * 0.50 = 46.8

The cost per week of electricity is Rm 46.8

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