18. many appliances you use every day change electrical energy into other forms. when you use a toaster to toast bread, electrical energy is changed to ____ and ____.

A. Heat and sound
B. Light and sound
C. heat and light
D. Heat and nuclear

19. when you lighted a lamp or candle, the chemical energy of the lamp is changed into light energy, and at the same it can produce ___.

A. heat
B. sound
C. Electricity
D. chemical

20. When you plugged a transistor radio in an electrical outlet and switch on the power button, automatically the electrical energy is turned to _____.

A. heat energy
B. Sound energy
C. light energy
D. radiant energy​