तुरंत तैयार कर लो इन सवालों के जवाब, हर साल पूछे जाते हैं ये 12वीं की Physics बोर्ड परीक्षा में

12वीं फिजिक्स में कुछ कांसेप्ट बहुत ज़्यादा महत्वपूर्ण होते हैं और इनके ऊपर हर साल CBSE board, ICSE board और UP board जैसे बोर्ड एग्जाम में ज़रूर पूछे जाते हैं l हर साल, इन एग्जाम में 3 से 5 नंबर के कुछ सवाल ऐसे भी पूछे जाते हैं जिनमे लम्बे Derivations के साथ-साथ Diagrams वगैरह भी होते हैं l

किसी भी चीज को समझ कर याद करना अच्छी बात है मगर कुछ Derivations और Diagrams इतने ज़्यादा महत्वपूर्ण होते हैं उन्हें समझने के साथ-साथ लिखकर याद करना (या दूसरे शब्दों में रटना) बहुत ज़रूरी होता है l लिखकर याद करने का सबसे बड़ा फायदा यह होता है कि एग्जाम में अगर ऐसा सवाल आ जाए तो आपको रिकॉल करने में समय नहीं लगता और आप बहुत कम समय में उत्तर लिख सकते हैं l

कैसे करें किसी भी एग्जाम की तैयारी: जब बचा हो एक महीना या एक हफ्ता या फिर एक दिन

अगर हम पुराने 5 से 10 साल के पेपर्स की एनालिसिस करेंगे तो पाएंगे कि कुछ ख़ास कंसेप्ट्स पर हर साल सवाल पूछे जा रहे हैं l इस आर्टिकल में हमने CBSE 12th के पुराने 5 साल के महत्वपूर्ण सवाल छांट कर यहाँ लिखे हैं l यह सवाल घुमा फिरा कर हर साल पूछे जा रहे हैं l अगर आप UP board या दूसरे स्टेट बोर्ड के पेपर्स देखेंगे तो आप पाएंगे कि उन पेपर्स में भी कुछ इसी तरह के सवाल बार-बार पूछे गए हैं l यहाँ पर हमने 2017 की बोर्ड परीक्षा के भी महत्वपूर्ण सवाल शामिल किए हैं l क्यूंकि यह मुमकिन है कि जिन कांसेप्ट से जुड़े हुए सवाल वर्ष 2017 की परीक्षा में 5 नंबर के पूछें गए हैं वह सवाल 2018 की परीक्षा में 2 या 3 नंबर में भी पूछे जा सकते हैं l

आईए जानते है ऐसे ही कुछ महत्वपूर्ण सवाल:

Question:

Draw a labelled diagram of AC generator. Derive the expression for the instantaneous value of the emf induced in the coil. (CBSE 2017)
Question:

Draw a labelled diagram of a step-up transformer. Obtain the ratio of secondary to primary voltage in terms of number of turn and currents in the two coils. (CBSE 2017)

Question:

Distinguish between unpolarized light and linearly polarized light. How does one get linearly polarised light with the help of a polaroid? (CBSE 2017)

क्या नहीं लग रहा पढ़ाई में मन? ज़रा इन मॉडर्न तरीकों को आज़माओ और फिर देखो कमाल

Question:

Explain two features to distinguish between the interference pattern in Young's double slit experiment with the diffraction pattern obtained due to a single slit. (CBSE 2017)

Question:

Derive an expression for drift velocity of electrons in a conductor. Hence deduce Ohm's law. (CBSE 2017)

Question:

State the two Kirchhoff's laws. Explain briefly how these rules are justified. (CBSE 2017)

Question:

The current is drawn from a cell of emf E and internal resistance r connected to the network of resistors each of resistance r as shown in the figure. Obtain the expression for (i) the current draw from the cell and (ii) the power consumed in the network. (CBSE 2017)

Question:

An AC source of voltage V = V₀ sin ωt is connected to a series combination of L, C and R. Use the phasor diagram to obtain expression for impedance of a circuit and the phase angle between voltage and current. Find the condition when current will be in phase with the voltage. What is the circuit in this condition called? (CBSE 2016)

Question:

Write the function of a transformer. State its principle of working with the help of a diagram. Mention various energy losses in this device. (CBSE 2016)

Question:

In Young's double-slit experiment, deduce the condition for (a) constructive and (b) destructive interferences at a point on the screen. Draw a graph showing variation of intensity in the interference pattern against position 'x' on the screen. (CBSE 2016)

यह 7 ट्रिक्स अपनाने से कोई भी बन सकता हैं गणित में ज़ीरो से हीरो

Question:

Compare the interference pattern observed in Young's double-slit experiment with single-slit diffraction pattern, pointing out three distinguishing features. (CBSE 2016)

Question:

(i) Plot a graph to show variation of the angle of deviation as a function of angle of incidence for light passing through a prism. Derive an expression for refractive index of the prism in terms of angle of minimum deviation and angle of prism.

(ii) What is dispersion of light? What is its cause?

(iii) A ray of light incident normally on one face of a right isosceles prism is totally reflected, as shown in fig. What must be the minimum value of refractive index of glass? Give relevant calculations. (CBSE 2016)

Question:

(i) Define the term drift velocity.

(ii) On the basis of electron drift, derive an expression for resistivity of a conductor in terms of number density of free electrons and relaxation time. On what factors does resistivity of a conductor depend?

(iii) Why alloys like constantan and manganin are used for making standard resistors? (CBSE 2016)

Question:

(a) State Ampere's circuital law. Use this law to obtain the expression for the magnetic field inside an air cored toroid of average radius 'r', having 'n' turns per unit length and carrying a steady current I. (CBSE 2015)

Question:

(a) Define mutual inductance and write its S.I. units.

(b) Derive an expression for the mutual inductance of two long co-axial solenoids of same length wound one over the other,

(c) In an experiment, two coils c₁ and c₂ are placed close to each other. Find out the expression for the emf induced in the coil c₁ due to a change in the current through the coil c₂. (CBSE 2015)

Question:

(a) Using Huygens's construction of secondary wavelets explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a monochromatic beam of light is incident normally.

(b) Show that the angular width of the first diffraction fringe is half that of the central fringe.

(c) Explain why the maxima at θ = (n + 1/2) λ/2 become weaker and weaker with increasing n. (CBSE 2015)

Question:

(a) A point object 'O' is kept in a medium of refractive index n₁ in front of a convex spherical surface of radius of curvature R which separates the second medium of refractive index n₂ from the first one, as shown in the figure. Draw the ray diagram showing the image formation and deduce the relationship between the object distance and the image distance in terms of n₁, n₂ and R.

(b) When the image formed above acts as a virtual object for a concave spherical surface separating the medium n₂ from n₁ (n₂ > n₁), draw this ray diagram and write the similar (similar to (a)) relation. Hence obtain the expression for the lens maker's formula. (CBSE 2015)

पेपर ऑब्जेक्टिव हो या सब्जेक्टिव: इन गलतियों की वजह से सब कुछ आते हुए भी नहीं आ पाते अच्छे मार्क्स

Question:

Question:

(a) (i) 'Two independent monochromatic sources of light cannot produce a sustained interference pattern'. Give reason.
(ii) Light waves each of amplitude "a" and frequency "ω", emanating from two coherent light sources superpose at a point. If the displacements due to these waves is given by y₁ = a cos ωt and y₂ = a cos(ωt + ϕ) where ϕ is the phase difference between the two, obtain the expression for the resultant intensity at the point.

(b) In Young's double slit experiment, using monochromatic light of wavelength λ, the intensity of light at a point on the screen where path difference is λ, is K units. Find out the intensity of light at a point where path difference is λ/3. (CBSE 2014)

Question:

(a) How does one demonstrate, using a suitable diagram, that unpolarised light when passed through a Polaroid gets polarised?

(b) A beam of unpolarised light is incident on a glass-air interface. Show, using a suitable ray diagram, that light reflected from the interface is totally polarised, when μ = tan i_B, where μ is the refractive index of glass with respect to air and i_B is the Brewster's angle. (CBSE 2014)

Question:

(a) Describe a simple experiment (or activity) to show that the polarity of emf induced in a coil is always such that it tends to produce a current which opposes the change of magnetic flux that produces it.

(b) The current flowing through an inductor of self inductance L is continuously increasing. Plot a graph showing the variation of

(i) Magnetic flux versus the current

(ii) Induced emf versus dI/dt

(iii) Magnetic potential energy stored versus the current. (CBSE 2014)

Question:

(a) State briefly the processes involved in the formation of p-n junction explaining clearly how the depletion region is formed.

(b) Using the necessary circuit diagrams, show how the V-I characteristics of a p-n junction are obtained in

(i) Forward biasing

(ii) Reverse biasing

How are these characteristics made use of in rectification? (CBSE 2014)
Question:

(a) Differentiate between three segments of a transistor on the basis of their size and level of doping.

(b) How is a transistor biased to be in active state?

(c) With the help of necessary circuit diagram, describe briefly how n-p-n transistor in CE configuration amplifies a small sinusoidal input voltage. Write the expression for the ac current gain.  (CBSE 2014)

Question:

(a) Draw a ray diagram showing the image formation by a compound microscope.

Hence obtain expression for total magnification when the image is formed at infinity.

(b) Distinguish between myopia and hypermetropia. Show diagrammatically how these defects can be corrected. (CBSE 2013)

Question:

(a) State Huygen’s principle. Using this principle draw a diagram to show how a plane wave front incident at the interface of the two media gets refracted when it propagates from a rarer to a denser medium. Hence verify Snell’s law of refraction.

(b) When monochromatic light travels from a rarer to a denser medium, explain the following, giving reasons:

(i) Is the frequency of reflected and reflected light same as the frequency of incident light?

(ii) Does the decrease in speed imply a reduction in the energy carried by light wave? (CBSE 2013)

Question:

(a) State the working principle of a potentiometer. With the help of the circuit diagram; explain how a potentiometer is used to compare the emf’s of two primary cells. Obtain the required expression used for comparing the emf’s.

(b) Write two possible causes for one sided deflection in a potentiometer experiment. (CBSE 2013)

Question:

(a) Derive the expression for the torque on a rectangular current carrying loop suspended in a uniform magnetic field.

(b) A proton and a deuteron having equal momenta enter in a region of uniform magnetic field at right angle to the direction of the field. Depict their trajectories in the field. (CBSE 2013)

Question:

(a) A small compass needle of magnetic moment ‘m’ is free to turn about an axis perpendicular to the direction of uniform magnetic field ‘B’. The moment of inertia of the needle about the axis is ‘I’. The needle is slightly disturbed from its stable position and then released. Prove that it executes simple harmonic motion. Hence deduce the expression for its time period.

(b) A compass needle, free to turn in a vertical plane orients itself with its axis vertical at a certain place on the earth. Find out the values of

(i) horizontal component of earth’s magnetic field and

(ii) angle of dip at the place. (CBSE 2013)

ये थे कुछ महत्वपूर्ण प्रश्न जो घुमा फिरा कर हर साल CBSE board, ICSE board और UP board जैसे एग्जाम में ज़रूर पूछे जाते हैं l एग्जाम में अच्छे मार्क्स लाने के लिए इन सवालों को और सवालों से जुड़े कंसेप्ट्स को बिल्कुल इग्नोर न करें l इसी आर्टिकल की तरह हम आपको जल्द ही गणित और रसायन विज्ञान जैसे विषयों के महत्वपूर्ण सवालों के बारे में भी बताएंगे l

इन पाँच तरीकों से बना सकते गणित को एक सरल और रोचक विषय, परीक्षा में आएंगे पूरे नंबर