WAEC Physics 2017 Objective — Question 38
Question 38 of 50 from the West African Examinations Council (WAEC) Physics 2017 Objective paper, with the correct answer and a full explanation.
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A galvanometer of internal resistance 50Ω and full scale deflection of 20mA is converted into a voltmeter by connecting a resistor of resistance 1950Ω in series to it. Calculate the maximum voltage that can be read by the voltmeter.
- A. A. 20V
- B. B. 30V
- C. C. 38V
- D. D. 40VCorrect
Explanation
Given: Rg=Resistance of the galvanometer=50Ω; current in circuit=20mA=0.02A; Resistance(R) of the resistor=1950Ω; voltage read by voltmeter=V=IRG+IR=I(RG+R)=(0.02x50)+(0.02x1950)=1+39=40V.
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