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Physics 4 Marks Questions

Model Paper 1 · Gujarat Board (GSEB) STD 12 Science (GSEB - English Medium). 6 questions.

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4 Marks Questions

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6 questions · self-marked practice — reveal the answer and mark yourself.

Question 14 Marks
An electron in hydrogen atom revolving in a radius of $5.29 \times 10^{11} m$ around the nucleus. According to the condition of Bohr's allowed electron orbits, find the principle quantum number corresponds to this orbit.
$\begin{array}{l}
h=6.625 \times 10^{-34} Js, e=1.6 \times 10^{-19} C \\
\varepsilon_0=8.85 \times 10^{-12} MKS, m=9.1 \times 10^{-31} kg \text { Find out conclusion from your answe }
\end{array}$
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Question 24 Marks
(a) Determine the electrostatic potential energy of a system consisting of two charges $7 \mu C$ and $-2 \mu C$ (and with no external field) placed at ( -9 cm $0,0)$ and ( $9 cm, 0,0$ ) respectively.
(b) How much work is required to separate the two charges infinitely away from each other?
(c) Suppose that the same system of charge is now placed in an external electric field $E=A\left(\frac{1}{r^2}\right) ; A=9 \times 10^5 NC ^{-1} m^2$. What would the electrostatic energy, of the configuration be?
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Question 34 Marks
The Q value of a nuclear reaction $A + b \rightarrow C +d$ is defined by $Q =\left[m_{ A }+\right.$ $\left.m_{ b }-m_{ C }-m_{ d }\right] c^2$ where the masses refer to the respective nuclei. Determine from the given data the Q -value of the following reactions and state whether the reactions are exothermic or endothermic.
(i) ${ }_1^1 H +{ }_1^3 H \rightarrow{ }_1^2 H +{ }_1^2 H$
(ii) ${ }_6^{12} C +{ }_6^{12} C \rightarrow{ }_{10}^{20} Ne +{ }_2^4 He$
Atomic masses are given to be :
$m \left({ }_1^2 H \right)=2.014102 u, m\left({ }_1^3 H \right)=3.016049 u$,$m \left({ }_6^{12} 12 C \right)=12.000000 u$ $m \left({ }_{10}^{20} Ne \right)=19.992439 u$
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Question 44 Marks
Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of $R =2 m$. If the jogger is running at a speed of $5 ms^1$, how fast the image of the jogger appear to move when the jogger is (a) 39 m , (b) 29 m, (c) 19 m , and(d) 9 m away.
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Question 54 Marks
Figure shows a series LCR circuit connected to a variable frequency 230 V source.
$\begin{array}{r}
L=5.0 H \cdot C=80 \mu F, R=40 \Omega \\
R=40 \Omega
\end{array}$
Image
(a) Determine the source frequency which drives the circuit in resonance.
(b) Obtain the impedance of the circuit and the amplitude of current at the resonating frequency.
(c) Determine the rms potential drops across the three elements of the circuit. Show that the potential drop across the LC combination is zero at the resonating frequency.
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