Question

1Q. The safe limits of loudness of audible sound for human is ____ to ____ dB.

2Q. Match the column:
a. prism i. banks and ATMs
b. refraction ii. shows refraction
c. dispersion iii. telescopes
d. concave mirror iv. splitting of white light
e. convex mirror v. mirage

3Q. Ria's study rooms has a bulb of 75 W which is used for 5 hours daily in the month of September.Calculate the electric energy consumed in the month.If the cost of electric energy is ₹2.75 per unit, calculate the expenditure for the month.

4Q. Give one-word answer:
• A form if mechanical energy produced by a vibrating object to complete one vibration _______.

5Q. True or False : The angle of reflection is equal to the angle of refraction, says the law of reflection.

​

Answer 1

Answer:

Q.1 120db

Q.2 a. banks and ATM'S

b.shows refraction

c. splitting if white light

d. telescopes

e. mirage

Q.3 75 w 4 hrs 30 days. So your total consumption is 75*4*30= 9000watt hr.

1 unit = 1000 watt hr.

9000 watt hr = 9 unit.

Total cost 9*2.5= RS 22.5

Q.4 Sound energy

Q.5 False

please mark me as a brainlist