Heat and Light Transducers

What is the specific heat of a material?

• The amount of heat energy required to raise the temperature of a material by 1°

• The total heat content of an object

• The time required to change the temperature of an object

• The heat transfer rate of a material

Which of the following is NOT a method of heat transfer?

• Conduction

• Convection

• Radiation

• Compression

Which material property determines the rate of heat conduction?

• Specific heat

• Thermal conductivity

• Electrical resistance

• Density

What is the main principle behind a thermocouple?

• Resistance changes with temperature

• Voltage is generated due to temperature differences at two junctions

• Expansion of liquid inside a tube

• Changes in gas pressure with temperature

What is the primary disadvantage of a bimetallic strip thermometer?

• It is expensive

• It is slow to respond

• It is highly inaccurate

• It cannot measure temperatures above 50°C

Which temperature sensor is best for measuring very high temperatures without direct contact?

• Thermistor

• Pyrometer

• Resistance Temperature Detector (RTD)

• Liquid-in-glass thermometer

Which of the following has the shortest wavelength?

• Infrared

• Ultraviolet

• Radio waves

• Microwaves

What unit is used to measure the brightness of light as perceived by the human eye?

• Watt

• Newton

• Lumen

• Ampere

Which type of light transducer converts light directly into an electrical signal?

• Photocell

• Thermistor

• Resistor

• Inductor

What is the main principle behind a phototransistor?

• Heat conversion

• Magnetic induction

• Light absorption

• Electrical resistance change