When an object is heated it …………… and when it cools it …………………..

When an object is heated it Expand and when it cools it Contract

Explanation:

One of the effect of heat on matter is expansion. An increase in the temperature of an object causes it to expand and a decrease causes it to contract

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27