Page 5 - ECAT Past Paper 2006

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A) Blue light B) Gamma rays
C) X-rays D) Red light (Correct)
Explanation:
As we know that:
For Visible spectrum:
(with increasing wavelength order)
:.VIBGYOR Red has longest wavelength
For Electromagnetic spectrum:
(with decreasing wavelength order)
According to it, wavelength order is:
Gamma rays > x-rays > Blue light > Red light
RMI-VU-XG
Q.14 Diffraction effect is:
A) more for round edge B) less for round edge
C) more for sharp edge (Correct) D) less for sharp edge
Explanation:
Diffraction is the bending process so it’s prominent more for sharp edges.
Q.15 Wavelength of x-rays falling at glance angle 30* on a crystal with atomic spacing 2*10 -
9 m for 1 order diffraction is:
st
-10
6
A) 4*10 m B) 2*10 m
-10
C) 0.2*10 m D) 20*10 m (Correct)
-10
Explanation:
Using Bragg’s Equation:
2dsinθ=m
2(2*10 )sin30*= 1*
-9
4*10 * ½ =
-9
-9
=2*10 m
-10
or = *10 m (Answer)
Q.16 In Photoelectric effect, the energy ejected electrons depend upon:
A) The frequency (Correct) B) The intensity
C) Both D) None of these
Explanation:
The number of emitted photo electrons depends upon the intensity of light.
 The maximum energy of photoelectrons depends upon the surface of metal and the
frequency of incident light.
Q.17 The normal distance for human eye is:
A) 30 cm B) 40 cm
C) 25 cm (Correct) D) 20 cm
Explanation:
The least distance/near point for human eye are as respectively:
 For Children: 10 cm
 For Young: 25 cm
 For Old: 40 cm
For normal distance, we always consider for the young people.
Q.18 The process in which the pressure remains constant is called:
A) isothermal B) Adiabatic
C) isobaric (Correct) D) isochoric
Explanation:
 Isochoric: the process in which volume remains constant.
 Isobaric: the process in which pressure remains constant.
 Isothermal: the process in which temperature remains constant.
 Adiabatic: the process in which temperature varies.
Q.19 How many processes does a four stroke engine undergo?
A) 2 B) 3