A 234- resistor and a 592- resistor are connected in series across a 900-V line.

Question

A 234- resistor and a 592- resistor are connected in series across a 900-V line. (a) What is the voltage across each resistor? V592 - (b) A voltmeter connected across the 234- resistor reads 23.8 V. Find the voltmeter resistance (c) Find the reading of the same voltmeter if it is connected across the 592- resistor. (d) The readings on this voltmeter are lower than the "true" voltages (that is, without the voltmeter present). Would it be possible to design a voltmeter that gave readings higher than the "true" voltages? Yes No Explain

Explanation / Answer

A. a 234 ohm resistor is in series with 592 ohm resistor

the equivalent resistance = 234 + 592 = 826 ohm

current in the line = potential difference / the equivalent resistance = 90 /826 A

so potential difference across 234 ohm resistor V234 = current x 234

= (90/826) x 234 = 25.496 V

potential difference across 592 ohm resistor V592 = current x 592

= (90/826) x 592 = 64.504 V

b. voltmeter reading is 23.8 V

True voltage = 25.496 V

so potential drop across the voltmeter = 25.496 - 23.8 = 1.696 V

resistance of the voltmeter = 1.696/current = 15.566 ohm

c. If the same voltmeter is connected across 592 ohm resistor,

the potential drop across the voltmeter = 1.696 V

true potential difference across 592 ohm =64.504 V

so reading of the voltmeter when connected across 592 ohm resistor = 64.504 - 1.696 = 62.808 V

d. No. It is not possible because for giving higher reading than the true voltage, the voltmeter has to contribute some voltage. As voltmeter cannot create voltage, so it is not possible.

all the best in the course work

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