Current Electricity

1Drift velocity of electrons in a conductor is typically of the order:

• A10⁻⁴ m/s
• B10⁻² m/s
• C10⁶ m/s
• DSpeed of light

2Kirchhoff's voltage law states that:

• AThe sum of currents at a junction is zero
• BThe sum of EMFs around a closed loop equals zero (after accounting for drops)
• CResistance is proportional to length
• DPower = V²/R

3A potentiometer is most useful for measuring:

• AVery small EMFs accurately
• BVery large currents
• CResistance directly
• DCapacitance

4Wheatstone bridge is balanced when:

• AI through galvanometer is maximum
• BP/Q = R/S
• CP × S = Q × R only when all four are equal
• DVoltage is zero across the source

5If a wire of resistance R is stretched to twice its length, its new resistance is:

• AR
• B2R
• C4R
• DR/2