How will the image formed by a convex lens be affected if the central portion of the lens is wrapped in a black paper?
Question types
MODEL PAPER 9 question types
38 questions across 6 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
38
Questions
6
Question groups
5
Question types
01
M.C.Q (1 Marks)
12 Q→02Assertion (A) & Reason (B) MCQ
4 Q→032 Marks Questions
6 Q→043 Marks Question
8 Q→054 Marks Questions
2 Q→065 Marks Questions
6 Q→Sample Questions
MODEL PAPER 9 questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
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In the given figure, a diode D is connected to an external resistance $R =100 \Omega$ and an emf of 3.5 V . If the barrier potential developed across the diode is 0.5 V , the current in the circuit will be
View full solution →A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will:
If the percentage change in current through a resistor is $1\%,$ then the change in power through it would be:
View full solution →In Young's double$-$slit experiment, the intensity of light at a point on the screen where the path difference is $\lambda$ is $k ( \lambda$ being the wavelength of light used$)$. The intensity at a point where the path difference is $\frac{\lambda}{4},$ will be
View full solution →Assertion: Positive charge always moves from a higher potential point to a lower potential point.
Reason: Electric potential is a vector quantity.
Reason: Electric potential is a vector quantity.
Assertion (A): In photoemissive cell inert gas is used.
Reason (R): inert gas in the photoemissive cell gives greater current.
Reason (R): inert gas in the photoemissive cell gives greater current.
Assertion (A): The dc and ac both can be measured by a hot wire instrument.
Reason (R): The hot wire instrument is based on the principle of magnetic effect of current.
Reason (R): The hot wire instrument is based on the principle of magnetic effect of current.
Assertion (A): In Young’s double-slit experiment if wavelength of incident monochromatic light is just doubled, number of bright fringe on the screen will increase.
Reason (R): Maximum number of bright fringe on the screen is inversely proportional to the wavelength of light used.
Reason (R): Maximum number of bright fringe on the screen is inversely proportional to the wavelength of light used.
$a$. Show that the time period $(T)$ of oscillations of a freely suspended magnetic dipole of magnetic moment $(m)$ in a uniform magnetic field $(B)$ is given by $T=2 \pi \sqrt{\frac{I}{m B}},$ where $I$ is a moment of inertia of the magnetic dipole.
$b$. Identify the following magnetic materials:
$i$. A material having susceptibility $\left(\chi_m\right)=-0.00015$.
$ii.$ A material having susceptibility $\left(\chi_m\right)=10^{-5}$.
View full solution →$b$. Identify the following magnetic materials:
$i$. A material having susceptibility $\left(\chi_m\right)=-0.00015$.
$ii.$ A material having susceptibility $\left(\chi_m\right)=10^{-5}$.
A deuteron and an alpha particle having same momentum are in turn allowed to pass through a magnetic field $\vec{B},$ acting normal to the direction of motion of the particles. Calculate the ratio of the radii of the circular paths described by them.
View full solution →A current I is flowing in an infinitely long conductor bent into the shape shown in Fig. If the radius of the curved part is R, find the magnetic field at the centre O.
Briefly explain Geiger-Marsden experiment. Show the variation of the number of particles scattered (N) with scattering angle $(\theta)$ in this experiment. What is the main conclusion that can be inferred from this plot?
View full solution →Explain the variation of resistivity with temperature in pure-semiconductors.
Consider a two $-$ slit interference arrangements $($Figure$)$ such that the distance of the screen from the slits is half the distance between the slits. Obtain the value of $D$ in terms of $\lambda$ such that the first minima on the screen fall at a distance $D$ from the center $O$.
View full solution →Find the equivalent resistance between the terminals $A$ and $B$ in the network shown in Figure. Given each resistor $R$ is $10 \Omega$.
View full solution →With the help of a circuit diagram, explain how two p-n junction diodes along with a centre tapped transformer can be used as a full wave rectifier.
A rectangular loop of wire $\text {ABCD}$ is kept close to an infinitely long wire carrying a current $I ( t )= l _0\left(1-\frac{t}{T}\right)$ for $0 \leq t \leq T$ and $I (0)=0$ for $t > T \ ($Figure$)$. Find the total charge passing through a given point in the loop, in time $T$ .
The resistance of the loop is $R$.
View full solution →The resistance of the loop is $R$.
$a$. A toroidal solenoid with an air core has an average radius of $0.15\ m,$ area of cross section $12 \times 10^{-4} m^2$ and $1200$ turns. Obtain the self inductance of the toroid. Ignore field variation across the cross section of the toroid.
$b$. A second coil of $300$ turns is wound closely on the toroid above. If the current in the primary coil is increased from zero to $2.0 A$ in $0.05\ s,$ obtain the induced emf in the secondary coil.
View full solution →$b$. A second coil of $300$ turns is wound closely on the toroid above. If the current in the primary coil is increased from zero to $2.0 A$ in $0.05\ s,$ obtain the induced emf in the secondary coil.
In an electromagnetic wave both the electric and magnetic fields are perpendicular to the direction of propagation, that is why electromagnetic waves are transverse in nature. Electromagnetic waves carry energy as they travel through space and this energy is shared equally by the electric and magnetic fields. Energy density of an electromagnetic waves is the energy in unit volume of the space through which the wave travels.
(i) The electromagnetic waves propagated perpendicular to both $\vec{E}$ and $\vec{B}$. The electromagnetic waves travel in the direction of
(a) $\vec{E} \cdot \vec{B}$
(b) $\vec{B} \cdot \vec{E}$
(c) $\vec{E} \times \vec{B}$
(d) $\vec{B} \times \vec{E}$
(ii) Fundamental particle in an electromagnetic wave is
(a) photon (b) phonon (c) electron (d) proton
(iii) Electromagnetic waves are transverse in nature is evident by
(a) diffraction (b) interference (c) polarisation (d) reflection
OR
The electric and magnetic fields of an electromagnetic waves are
(a) in opposite phase and parallel to each other
(b) in phase and parallel to each other.
(c) in phase and perpendicular to each other
(d) in opposite phase and perpendicular to each other
(iv) d) in opposite phase and perpendicular to each other
(a) frequency (b) wavelength (c) velocity (d) all these depend on each other
View full solution →(i) The electromagnetic waves propagated perpendicular to both $\vec{E}$ and $\vec{B}$. The electromagnetic waves travel in the direction of
(a) $\vec{E} \cdot \vec{B}$
(b) $\vec{B} \cdot \vec{E}$
(c) $\vec{E} \times \vec{B}$
(d) $\vec{B} \times \vec{E}$
(ii) Fundamental particle in an electromagnetic wave is
(a) photon (b) phonon (c) electron (d) proton
(iii) Electromagnetic waves are transverse in nature is evident by
(a) diffraction (b) interference (c) polarisation (d) reflection
OR
The electric and magnetic fields of an electromagnetic waves are
(a) in opposite phase and parallel to each other
(b) in phase and parallel to each other.
(c) in phase and perpendicular to each other
(d) in opposite phase and perpendicular to each other
(iv) d) in opposite phase and perpendicular to each other
(a) frequency (b) wavelength (c) velocity (d) all these depend on each other
$a.$ Derive the expression for the current flowing in an ideal capacitor and its reactance when connected to an ac source of voltage $V = V _{ o } \sin \omega t$.
$b.$ Draw its phasor diagram.
$c.$ If resistance is added in series to capacitor what changes will occur in the current flowing in the circuit and phase angle between voltage and current.
View full solution →$b.$ Draw its phasor diagram.
$c.$ If resistance is added in series to capacitor what changes will occur in the current flowing in the circuit and phase angle between voltage and current.
You have learned in the text how Huygens’ principle leads to the laws of reflection and refraction. Use the same principle to deduce directly that a point object placed in front of a plane mirror produces a virtual image whose distance from the mirror is equal to the object distance from the mirror.
Draw a ray diagram to show the formation of real image of the same size as that of the object placed in front of a converging lens. Using this ray diagram establish the relation between u, v and f for this lens.
$i$. An ac source generating a voltage $V = V _0 \sin \omega t$ is connected to a capacitor of capacitance $C$ . Find the expression of the current $I$ flowing through it. Plot a graph of $V$ and $I$ versus $\omega t$ to show that the current is $\frac{\pi}{2}$ ahead of the voltage.
$ii$. A resistor of $200 \Omega$ and a capacitor of $15 \mu F$ are connected in series to a $220 V, 50 Hz$ ac source. Calculate the current in the circuit and the rms voltage across the resistor and the capacitor. Why the algebraic sum of these voltages is more than the source voltage?
View full solution →$ii$. A resistor of $200 \Omega$ and a capacitor of $15 \mu F$ are connected in series to a $220 V, 50 Hz$ ac source. Calculate the current in the circuit and the rms voltage across the resistor and the capacitor. Why the algebraic sum of these voltages is more than the source voltage?
Define the terms (i) capacitance of a capacitor (ii) dielectric strength of a dielectric. When a dielectric is inserted between the plates of a charged parallel plate capacitor, fully occupying the intervening region, how does the polarization of the dielectric medium affect the net electric field? For linear dielectrics, show that the introduction of a dielectric increases its capacitance by a factor $\kappa$, characteristic of the dielectric.
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