Question

If sound wave C has 100,000 times the intensity of sound wave D, then C has a sound level of how many decibels greater than D?

A: 50 dB

B: 10000 dB

C: 40dB

D: 10 dB

E: 100dB

At a very low frequency(such as 50 Hz), the human ear has more sensitivity to sound level compared to a medium frequency(such as 2000 Hz).

A False

B True

Light is fundamentally both a particle and a wave.

A False

B True

Suppose you have a single bar magnet with a north pole and a south pole. If you break it in half, with the break occuring in between the two poles, each half will still be magnetic. In other words, you will now have two magnets. One of your magnets will have no south pole and the other one will have no north pole.

A False

B True

A student makes four measurements of the length of a table. The results are 2m, 2.4m, 2.3m and 2.3m. What is the experimental value for the length?

A 1.80m

B 4.50m

C 9.00m

D 3.00m

E 2.25m

The main purpose of an oscilloscope is to generate a voltage

A False

B True

An oscilloscope can make a graph of voltage versus time.

A False

B True

I need the process or explanation. Thank you!

Answer 1

Q1.

sound level in dB=10*log10(intensity/I0)

where I=10^(-12) W/m^2

then if there are two different intensities I1 and I2,

then their difference in dB=10*log10(I2/I1)

here I2/I1=100000

hence difference in dB=10*log10(100000)=50 dB

Q2.

false.

humans are most sensitive to frequency between 2000 Hz and 5000 Hz.

Q3. true

Q4. False

single pole does not exist. once you break a magnet,

it automatically creates north pole and south pole at the two ends

Q5. experimental value will be the average value

=(2+2.4+2.3+2.3)/4=2.25 m

hence option D is correct.

Q6. false

oscilloscope is used to see the waveforms..

Q7. true