Question

What is the function of a speaker?

	1.	convert digital electrical signals into analog electrical signals
	2.	convert analog electrical signals into digital electrical signals
	3.	convert sound waves into analog electrical signals
	4.	convert sound waves into digital electrical signals
	5.	convert digital electrical signals into sound waves
	6.	convert analog electrical signals into sound waves

Heat transferred due to the mixing of rising hot fluids and sinking cold fluids (assisted by gravity) is known as...

	1.	absorption
	2.	adsorption
	3.	combustion
	4.	conduction
	5.	convection
	6.	fluorescence
	7.	radiation

Answer 1

1)The speaker is a transducer and it's function is exactly opposite to that of the microphone. Microphone converts continuous sound signal in to an electric analog signals and it is further amplified (processed) and fed to the speaker which is one of the transducer which converts analog electric signals in to sound.

Hence option 6 is correct.

2)Transfer of Heat from one place to other place is occur by three different phenomenon 1)Conduction : In this process heat transfer from one place to other place by vibrating particles of medium.Particle of medium does not change their location they just vibrate about their mean position and transfer energy to next particle.2)Radiation: In this type heat transfer in the form of electromagnetic waves. There is no need of material medium. 3)Convection:In this type of heat transfer particle of medium moves from one place to another place and also carry heat energy with them. For example in the process of water heating warm water goes to to top region while cold water bears high density comes to bottom due to gravity.

Hence option 5 is correct.