Answer:
The observer detects light of wavelength is 115 nm.
(b) is correct option
Explanation:
Given that,
Wavelength of source = 500 nm
Velocity = 0.90 c
We need to calculate the wavelength of observer
Using Doppler effect
Where, 
Hence, The observer detects light of wavelength is 115 nm.
Answer:
The quantities which do not depend on other quantities is called fundamental qiantity. For eg; time,current,lwngth etc...
In Burglar alarm, LDR acts an AND gate.
Answer: C
Explanation
The LDR is light dependent resistor. The principle used in the working of LDR is that the resistance is inversely proportional to the intensity of light falling on the diode.
In burglar alarm, LDR diode is combined with an IC 555.
Normally an LED source is made to be incident on the LDR diode with same intensity such that the resistance will be maintained constant.
As the LDR is connected with IC, the voltage will be high when light is falling on the diode.
The IC will give only two output states that is high and low. This confirms that LDR in burglar alarm act as AND gate.
As the thief enters and crosses the LED light, the intensity of the light falling on the diode will decrease leading to decrease in the voltage which will cause the alarm to beep.
Answer:primary,secondary and surface waves I do believe
Explanation:
Answer:
h≅ 58 m
Explanation:
GIVEN:
mass of rocket M= 62,000 kg
fuel consumption rate = 150 kg/s
velocity of exhaust gases v= 6000 m/s
Now thrust = rate of fuel consumption×velocity of exhaust gases
=6000 × 150 = 900000 N
now to need calculate time t = amount of fuel consumed÷ rate
= 744/150= 4.96 sec
applying newton's law
M×a= thrust - Mg
62000 a=900000- 62000×9.8
acceleration a= 4.71 m/s^2
its height after 744 kg of its total fuel load has been consumed
h= 58.012 m
h≅ 58 m
