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The order of coloured rings in a carbon resistor is red, yellow, blue and silver. The resistance of…
(A)(i)[1.0]
The order of coloured rings in a carbon resistor is red, yellow, blue and silver. The resistance of the carbon resistor is:
- (a)$24 \times 10^6\ \Omega \pm 5\%$
- (b)$24 \times 10^6\ \Omega \pm 10\%$
- (c)$34 \times 10^4\ \Omega \pm 10\%$
- (d)$26 \times 10^4\ \Omega \pm 5\%$
(A)(ii)[1.0]
A circular coil carrying a current $I$ has radius $R$ and number of turns $N$. If all the three, i.e. the current $I$, radius $R$ and number of turns $N$ are doubled, then, magnetic field at its centre becomes:
- (a)Double
- (b)Half
- (c)Four times
- (d)One fourth
(A)(iii)[1.0]
An object is kept on the principal axis of a concave mirror of focal length $10\text{ cm}$, at a distance of $15\text{ cm}$ from its pole. The image formed by the mirror is:
- (a)Virtual and magnified
- (b)Virtual and diminished
- (c)Real and magnified
- (d)Real and diminished
(A)(iv)[1.0]
Einstein’s photoelectric equation is:
- (a)$E_{\max} = h\lambda - \varphi_0$
- (b)$E_{\max} = \frac{hc}{\lambda} - \varphi_0$
- (c)$E_{\max} = h\nu + \varphi_0$
- (d)$E_{\max} = \frac{hc}{\lambda} + \varphi_0$
(A)(v)[1.0]
In Bohr's model of hydrogen atom, radius of the first orbit of an electron is $r_0$. Then, radius of the third orbit is:
- (a)$\frac{r_0}{9}$
- (b)$r_0$
- (c)$3 r_0$
- (d)$9 r_0$
(B)(i)[1.0]
In a potentiometer experiment, balancing length is found to be $120\text{ cm}$ for a cell $E_1$ of emf $2\text{V}$. What will be the balancing length for another cell $E_2$ of emf $1\cdot5\text{V}$? (No other changes are made in the experiment.)
(B)(ii)[1.0]
How will you convert a moving coil galvanometer into a voltmeter?
(B)(iii)[1.0]
A moving charged particle $q$ travelling along the positive x-axis enters a uniform magnetic field $B$. When will the force acting on $q$ be maximum?
(B)(iv)[1.0]
Why is the core of a transformer laminated?
(B)(v)[1.0]
Ordinary (i.e. unpolarised) light is incident on the surface of a transparent material at the polarising angle. If it is partly reflected and partly refracted, what is the angle between the reflected and the refracted rays?
(B)(vi)[1.0]
Define coherent sources of light.
(B)(vii)[1.0]
Name a material which is used in making control rods in a nuclear reactor.
Answer
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From ISC 2018 Physics Paper 1, question 1.