Question

State the energy changes in the following cases while in use:
(a) an electric bulb
(b) an electric oven
(c) loudspeaker
(d) microphone
(e) Electric motor

Answer 1

Energy is the quantitative quality that must be delivered to a body or physical system in order to perform work on or heat an item in physics. Energy is a conserved quantity, meaning it may be transformed in form but not generated or destroyed, according to the rule of conservation of energy. The joule is the energy delivered to an item by the effort of moving it a distance of one metre against a force of one newton, as defined by the International System of Units (SI).

Complete answer:
(a) Electric energy is turned to light and heat in the case of an electric bulb. The quantity of electrical energy put into a bulb is equal to the sum of the light energy (desirable form) and the heat energy emitted by the bulb (undesirable form). Incandescent light bulbs are devices that use electric current to heat a filament until it releases electromagnetic radiation, converting electricity into light. The filament's high resistance causes its temperature to increase until it glows when electricity travels through it.

(b) Heating elements are used in traditional electric ranges, cooktops, and ovens to convert electrical energy into heat energy. In typical ovens, this heat energy is transferred by radiation and convection to the pans containing the food, and then by conduction to the food to be cooked. An oven transforms electrical energy into heat energy, a toaster translates electrical energy into heat energy, and an alarm clock converts electrical energy into light and sound energy.

(c) Unlike microphones, which convert sound energy into diaphragm motion and hence into electrical signals, loudspeakers transfer electrical energy into diaphragm motion and hence into sound energy. Electrical energy is converted into mechanical energy by speakers (motion). Mechanical energy compresses air and transforms motion into sound energy or sound pressure level (SPL). A magnetic field is created when an electric current is sent through a coil of wire.

(d) In a microphone, there is an energy shift that occurs. Electrical energy is converted from sound energy. Sound is converted into a tiny electrical current via a microphone. Sound waves strike a vibrating diaphragm, which moves a magnet toward a coil. Sound waves are converted into electrical impulses by the microphone. Microphones employ the generator effect to generate a variable current based on sound wave pressure fluctuations.

(e) Electromagnetic induction is the technique through which an electric motor turns electrical energy into mechanical energy. An electric motor is a mechanism that turns electricity into mechanical energy. The interaction between the motor's magnetic field and electric current in a wire winding generates force in the form of torque imparted to the motor's shaft in most electric motors.

Note: The law of conservation of energy asserts that the total energy of an isolated system remains constant; it is stated to be conserved throughout time in physics and chemistry. Energy cannot be generated or destroyed, according to this law, which was initially suggested and tested by Émilie du Châtelet. Instead, it can only be converted or moved from one form to another. When a stick of dynamite explodes, chemical energy is transferred to kinetic energy.