A galvanometer with a full-scale deflection of 20 mA is Converted to read 8 K by connecting a $395\,\Omega$ resistor in series with it. Determine the inte...

Assessment: WAEC SSCE - Physics - 2022 Subject: Physics

Question 1 Report

A galvanometer with a full-scale deflection of 20 mA is Converted to read 8 K by connecting a $395\,\Omega$ resistor in series with it. Determine the internal resistance of the galvanometer

2.5

Ω

5.0

Ω

8.0

Ω

10.0

Ω

Answer Details

r = resistance of the galvanometer

l = current through galvanometer = 20mA or 0.02A

V1 = p.d across the galvanometer = I X r = 0.02 X r

: V1 = 0.02r

V2 = p.d across the multiplier = 8 - 0.02r

R = resistance of the multiplier = 395Ω

where R = $\frac{V}{I}$

--> 395 = $\frac{8 - 0.02 r}{0.02}$

CROSS MULTIPLY

8−0.02r = 395 * 0.02

8−0.02r = 7.9

--> 0.02r = 8 - 7.9

∴ r = $\frac{0.1}{0.02}$

= 5Ω

Read lesson note on Electrostatics (JAMB)

Electrostatics

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A galvanometer with a full-scale deflection of 20 mA is Converted to read 8 K by connecting a \(395\,\Omega\) resistor in series with it. Determine the inte...

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A galvanometer with a full-scale deflection of 20 mA is Converted to read 8 K by connecting a \(395\,\Omega\) resistor in series with it. Determine the inte...

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