Can anyone help me solving these problems:(adsbygoogle = window.adsbygoogle || []).push({});

1. A tension of 5V is measured between the ends of a wire. What was the work done by the electric field while a charge of 100C was passing through a cross-section of a wire? What is the resistance of the wire if the current flow lasted for 23 seconds?

2. The pressure reqired for the water system of a town consisting of four-storey buildings is that of a 24 m high water colunm. What is the daily consumption of electric energy used for the water system of a town with a popolation of 50000 if we count with a daily average of 100l per capita and if the efficiency of the pumps is 80% whereas that of the electric motors is 92%.

3. Concrete blocks, each having a mass of 2.4tons, must be transfered to a height of 16m and one block must be lifted every half minute.

The voltage of the elevator motor is 220V; its efficiency is 90%.

a) what is the power of the motor while lifting a block?

b) What is its current consumption during this time?

c) What is the electric energy used for the lifting of one block?

d) What does the electric elnergy used for lifting of one block cost?

(the price of 1kWh is 1.20Ft)

4. An aluminium wire and a copper wire, both of the same lenght, are connected in series to a battery. Equal amounts of heat are generated in them in equal times. what is the ratio between the cross sectional areas of the two wires?

5. We connect an incandescent lamp designed for a power of 24 W and a voltage of 12 V to a bettery having an internal resistance of 8 ohm. The voltage drop across the lamp has just the required value!

a) What is the electromotive force of the battery?

b) What is the efficiency of the circuit?

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# Homework Help: Need help with problem!

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