# Physics 2018 | Study Mode

Question 41
A
2A
B
3A
C
5A
D
8A
##### Explanation

Ammeters are connected in series so,

A3= A2 + A1

A1 = A3 - A1

= 5A - 2A

= 3A

Question 42
A
pass through even non-magnetic materials
B
run from the north pole to the south pole
C
are in a state of tension and tend to be shorted
D
intersect one another
##### Explanation

Two magnetic lines of force can not intersect each other.

Question 43
A
Investigation of high voltages
B
Study of electric discharge
C
Operation of X-ray tubes
D
A.C. power transmission
##### Explanation

Question 44
A
4.1$$\Omega$$
B
5.0$$\Omega$$
C
10.8$$\Omega$$
D
11.2$$\Omega$$
##### Explanation

The impedance for a RLC circuit is

$$Z = \sqrt{R^{2} + (X_{L} - X_{C})^{2}}$$

= $$\sqrt{10^{2} + (9 - 4)^{2}}$$

= $$\sqrt{125}$$

= 11.18$$\Omega$$ $$\approxeq$$ 11.2$$\Omega$$

Question 45
A
A
B
B
C
C
D
D
##### Explanation

By convention, the field direction is taken to be outward from the North pole and in to the South pole of the magnet. Also, they form closed lines.

Question 46
A
$$\alpha$$- particles and $$\beta$$- particles
B
$$\alpha$$- particles and X-rays
C
$$\beta$$- particles and X-rays
D
$$\lambda$$- rays and X-rays
##### Explanation

In the course of natural radioactivity, alpha, beta and gamma rays are emitted.

Question 47
A
I, II and IV only
B
I, III and IV only
C
III and IV only
D
I and II only

Question 48
A
Gamma ray
B
C
Infrared ray
D
X-ray
##### Explanation

Radio wave has the longest wavelength and shortest frequency.

Question 49
A
Medicine
B
Oil industry
C
Agriculture
D
Weather forecast

Question 50
A
0.5
B
0.8
C
1.2
D
1.5
##### Explanation

The element B has a mass number of 70 with atomic number 32. Hence, B has 32 protons and (70-32) = 38 neutrons.

The neutron- proton ratio is 38:32 = $$\frac{38}{32} = 1.1875$$

$$\approxeq 1.2$$

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