Answer:
Image distance of apple=-6.7 cm
Magnification of apple=0.33
Explanation:
We are given that an apple is placed 20.cm in front of a diverging lens.
Object distance=u=-20 cm
Focal length=f=-10 cm
Because focal length of diverging lens is negative.
We have to find the image distance and magnification of the apple.
Lens formula

Substitute the values then we get




Image distance of apple=-6.7 cm
Magnification=m=
Magnification of apple=
Hence, the magnification of apple=0.33
Explanation:
Power of electric kettle, P = 1 kW
Voltage, V = 220 V
(a) Electric power is given by the formula as follows :

R is resistance

(b) When connected to a 220 V supply, it takes 3 minutes for the water in the kettle to reach boiling point.
Energy supplied is given by :

P is power, 

Amplitude: How dense the medium is in the compression part of the wave, and how empty the rarefied area is.
Frequency: The number of wavelengths that pass a position in 1 second.
loudness: The quality of the sound that is most closely linked to the amplitude of the sound wave.
Period: The amount of time that it takes one wavelength to pass by a position.
Pitch: The quality of the sound that is most closely linked to the frequency of the sound wave.