Class 4 (4th Engineer) MET 📅 Aug 2022

Exam Question

(a) State the relationship between impedance, voltage and current (6)

(b) The filament of a 230V lamp takes a current of 0.261A when working at its normal temperature of 2000°C. The temperature coefficient of the tungsten filament material can be taken as 0.005 ohms at 0°C. Find the approximate current which flows at the instant of switching on the supply to the cold lamp, which can be considered to be at room temperature of 20°C

Reference Answer

### (a) Relationship Between Impedance, Voltage, and Current
**1. Definition of Impedance (Z):**
Impedance is the total opposition that a circuit presents to an alternating current (AC). It is a complex quantity that extends the concept of resistance to AC circuits. Impedance includes both resistance (which dissipates energy as heat) and reactance (which stores energy in electric or magnetic fields).
* **Resistance (R):** The opposition to current flow that is independent of frequency. It is caused by components like resistors.

Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.

View plans Browse library

← Browse more questions

Prepare on Android — MeoMock on Google Play