A laboratory timer circuit uses a resistor in series with a capacitor

PHYSICS · Single correct · CBSE · Physics · Electrostatic Potential and Capacitance · Electrostatic Potential and Capacitance

Problem

A laboratory timer circuit uses a 25 kΩ25\,k\Omega resistor in series with a 4.7 μF4.7\,\mu\text{F} capacitor. Engineers find the circuit takes longer than desired to reach 63\% of its final charge. Which of the following component substitutions would most effectively reduce that charging time while leaving all other parts unchanged? (a) Connect a second 4.7 μF4.7\,\mu\text{F} capacitor in parallel with the existing one (b) Increase the battery voltage from 6 V6\,\text{V} to 9 V9\,\text{V} (c) Replace the 4.7 μF4.7\,\mu\text{F} capacitor with a 2.2 μF2.2\,\mu\text{F} capacitor (d) Replace the 25 kΩ25\,k\Omega resistor with a 47 kΩ47\,k\Omega resistor

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