# Physics 2015 | Study Mode

Question 41
A
Proton
B
Neutron
C
Electrons
D
Atoms
##### Explanation
Electron: A subatomic particle haring a negative charge and orbiting the nucleus (note: the symbol 01e represent the particle of an electrons.)

Question 42
A
2 1018HZ
B
3 10 19HZ
C
3 1021HZ
D
3 10-19HZ
##### Explanation

$$Wavelength (\lambda) = 10^{-13}m$$

Speed of X-ray = speed of light $$C = 310^{8}m/s$$

Frequently (f) = ?

$$Using V = f\lambda (or ( f for electromagnetic wave)$$

$$f = \frac{c}{\lambda} = 3 \times 10^{8} 10^{-13} = 3 \times 10^{8} \times 10^{13}$$

= $$3 \times 10^{8} \times 10^{13}$$

= $$3 \times 10^{21}Hz$$

Question 43
A
Increase in the number of turn of the coil
B
Decrease in current with the coil
C
Increase in the distance between the pole
D
Increase in current without the coil
##### Explanation
Note: the strength of an electromagnet increase with a decrease in the number of turns of the coil other are(ii) increase in current with in the coil

Question 44
A
15C
B
40C
C
20C
D
10C
##### Explanation
R0 = 7 , R1 = 7.2 , R2 = 7.5 , Tx = ?

[(X T100C) (R1 - R0)] = [(T100C T0C) (R2 - R0)]

[(Tx 0) (72 7)] = [(100 0) (7.5 7)]

Tx/0.2 = (100 0.5)

Tx = [(0.2 100)] 0.5

= 20/0.5 = 40C

Question 45
A
15Nm
B
25Nm
C
3Nm
D
4Nm
##### Explanation

Question 46
A
I & II only
B
II only
C
I, II, & III only
D
III only
##### Explanation
Fig (I) (II) (III) are they in which a transformer was designed to reduce an energy loses by reducing through this collective designed or efforts

Question 47
A
Mercury only
B
Alcohol and Water
C
Mercury and Alcohol
D
Alcohol only
##### Explanation
Mercury and alcohol are often used in THERMOMETER

Note:Water is never allowed to be used in thermometer because, it doesnt expand uniformly

Question 48
A
J.J. Thompson
B
C
D
Dalton
##### Explanation
Neutron were discovered by James Chadwick in 1931

Question 49
A
27m/s2
B
2m/s2
C
4m/s2
D
7m/s2
##### Explanation
For maximum range (Rmax)

Rmax = U2 g where Rmax = 36m, U2 = ?, g = 9.8m/s2

36 = U2 2 8.8

U2 = 36 2 9.8m = 705.8

U = 705.6 = 26.5 (squaring both side)

u= 26.5m/s, U = 27m/s (Approx.)

The speed of projection = 27m/s2

Question 50
A
kg m-2
B
kg m2
C
kg cm3
D
has no S.I unit
##### Explanation
Note: relative density has no S.I unit

Relative density = weight of substance weight of equal volume of water

RD = w1 (w1 w2) (no S. I unit)

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