Magnetism

Concept: To convert a voltmeter into an ammeter, a shunt resistance is connected in parallel. Key idea:
Voltmeter full-scale current $I_v%20%3D%20%5Cfrac%7BV%7D%7BR_v%7D$
Shunt carries remaining current
Same voltage across voltmeter and shunt
Step 1: Find full-scale current of voltmeter Given: $V%20%3D%20150%5C%2C%5Ctext%7BV%7D%2C%20%5Cquad%20R_v%20%3D%20300%5C%2C%5COmega$ $I_v%20%3D%20%5Cfrac%7BV%7D%7BR_v%7D%20%3D%20%5Cfrac%7B150%7D%7B300%7D%20%3D%200.5%5C%2C%5Ctext%7BA%7D$ So, voltmeter allows maximum current of $0.5%5C%2C%5Ctext%7BA%7D$ .
Step 2: Total current required Desired ammeter range: $I%20%3D%208%5C%2C%5Ctext%7BA%7D$ Current through shunt: $I_s%20%3D%20I%20-%20I_v%20%3D%208%20-%200.5%20%3D%207.5%5C%2C%5Ctext%7BA%7D$ Step 3: Voltage across shunt Voltage across voltmeter (and shunt in parallel): $V%20%3D%20I_v%20%5Ctimes%20R_v%20%3D%200.5%20%5Ctimes%20300%20%3D%20150%5C%2C%5Ctext%7BV%7D$ Step 4: Calculate shunt resistance $R_s%20%3D%20%5Cfrac%7BV%7D%7BI_s%7D%20%3D%20%5Cfrac%7B150%7D%7B7.5%7D%20%3D%2020%5C%2C%5COmega$ Final Answer: $%5Cboxed%7BR_s%20%3D%2020%5C%2C%5COmega%7D$

High-Yield Trend

Chapter Questions
2 MCQs

Official Solution

Official Solution

Magnetism

High-Yield Trend

Chapter Questions 2 MCQs

Official Solution

Official Solution

Chapter Questions
2 MCQs