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option 4

angle between a and b = 30°

angle between b and c = 90°

angle between a and c = (90+30) = 120°

solve Kar ke bhejiye

what do you need to be solved here.. its more of visual questions.. than theoretical .

you have mentioned angle between a and b -30°

and angle between b and c = 90°

now just move the c vector at the tail of a vector you will get angle between a and c as (90+30) = 120°

He should strech the wire upto 200cm for getting 4 ohm resistance as R =ρ*l/Atherefore 1 =ρ*50/A andρ/A = 1/50 ---------- (1) Now resistance = 4 ohm R =ρ*l/A4=ρ*l/Afrom (1)ρ/A = 1/50 so 4 = (1/50) land l = 200cm

Myopia

Near-sightedness : A person with Myopia can see nearby objects clearlyA person with myopia cannot see faraway objects clearly.

Occurs due to

1.Excessive curvature of the eye lens

2.Elongation of eyeball

3.The image of a distance object is formed in front of the retina and not on the retina

Defected is corrected by using Concave lenses such that the lens will bring the image back on to the retina.

Newton's law of universal gravitation states that every particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers

to measure the current

the current direction is from positive positive to negativein the lower branch the current direction is from negative to positive hence it should be reversed

the voltmeter should be connected in parallel and ammeter should be connected in series. In other words, replace the positions of the two meters from one another.

(a) Least count = Value measured in n divisions/n= 1.5/10 = .15 volts

(b) The reading shown by voltmeter = 1.5 +.3 = 1.8 volts

(c) V = I * R V = 1.8 R = 20 ohm Therefore, I = 1.8/20 = .09 ampere

when the resistance is infinite of the voltmeter thenR=V/I=120/2=60ohmwhen it has some high finite value then the value of R will be slightly greater

Theinternalresistanceoftheammeterisverylow.Ifweconnectitinseries,then themaximumcurrentcanflowthroughit.Sotheaccuratecurrentshouldbe measured.Ifweconnectitinparallelthentheaccuratecurrentcan’tbe measured.

OPtion A is correct.

Anammeter is connected in serieswith the circuit because the purpose of theammeteris to measure the current through the circuit. Since theammeteris a low impedance device,connectingit inparallelwith the circuit would cause a short circuit, damaging theammeterand/or the circuit

An ammeter is a LOW RESISTANCE device and is connected in series so as the whole circuit current flows through it for an accurate measurement.

The ammeter is connected in series with the circuit in which the current is to be measured, whereas the voltmeter is connected across the points where the potential difference is to be measured.

I = 5 A Resistance = RI' = 4 A R' = R+2 Ω = total resistance

We assume R is the total effective resistance in the circuit in series with the battery. Also, that 2 Ω resistance is added in series with the= given resistance and battery.

Voltage of the battery = E = I R = I' R' 5 * R = 4 ( R +2) => R = 8 Ω battery potential is = 40 V

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i=2.5, I through R1 ,R2,R3 and R4 is 2.5,1,3,and 2,5

i=2.5, I through R1,R2,R3 and R4 is 2.5,1,3, and2,5

Ans :- Advantages of parallel combination over series combination are:1) In parallel combination each appliance gets the full voltage.

2) If one appliance is switched on/of others are not affected.

3) The parallel circuit divide the current through the appliances. Each appliance gets proper current depending on its resistance.

4) In a parallel combination it is very easy to connect or disconnect a new appliance without affecting the working of other appliances.

5)In contrast, aseries circuitonly has one pathway for electricity to flow. If one component fails, the other components will also not work vs. aparallel circuitarrangement that allows electricity to flow through more thanone path – if one component fails, the others won't be affected.

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It damage the whole ciruts and objects

disadvantages:1) if one circuit breaks then entire circuit will fail.2 ) in series combination the resistances adds up leading high temperature.3) equal current is provided so items requiring low current get higher Current so they can overload .

Answer is option d). which is Resistance/Impedance

AnRLC circuit(orLCR circuit) is anelectrical circuitconsisting of aresistor, an inductor, and a capacitor, connected in series or in parallel. The RLC part of the name is due to those letters being the usual electrical symbols forresistance,inductanceandcapacitancerespectively. The circuit forms aharmonic oscillatorfor current andresonatessimilarly to anLC circuit. The main difference stemming from the presence of the resistor is that any oscillation induced in the circuit decays over time if it is not kept going by a source. This effect of the resistor is calleddamping. The presence of the resistance also reduces the peak resonant frequency ofdampedoscillation, although the resonant frequency fordrivenoscillations remains the same as an LC circuit. Some resistance is unavoidable in real circuits, even if a resistor is not specifically included as a separate component. A pure LC circuit is an ideal that exists only intheory.

An important application is for tuning, such as in radio receivers or television sets, where they are used to a narrow range of frequencies from the ambient radio waves.

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TriacOptocoupler Application

The main advantage of opto-couplers is their high electrical isolation between the input and output terminals allowing relatively small digital signals to control much large AC voltages, currents and power

Monal is national bird of (c) Nepal

B can be written asF/evNow its way to answer

We know thatLeast count = Pitch / C. S divisionPitch = 2mm/4= 0.5 mm= 0.05cmL. C= 0.05cm/1000.0005 cmHit the like 👍

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We consider a particle of mass m is performing vertical circular motion of a circle of radius r.

at highest position, weight and tension in string both are along downward direction.now, at the highest position, T + mg = mv²/r .........(1) here, v = √(gh) it is velocity at uttermost position in case of string.so, T + mg = mg = 0

again, at lowermost position, weight and tension in string both are in opposite directions. tension acts radially inward while weight radially outward. now , at the lowermost position, T' - mg = mv'²/r ........(2)here, v = √(5gh), it is velocity at Lowest position in case of string.so, T' - mg = 5mgh , T' = 6mg now, difference in tension at lowest and uttermost point for a particle performing vertical circular motion = T' - T = 6mg.

It can measure accurately upto 1 cm.this accuracy can b increased by increasing the no. of divisions or by making divisions within each division of 1cm

Cyclotron is a device used to accelerate charged particles to high energies. It was devised by Lawrence.

Principle

Cyclotron works on the principle that a charged particle moving normal to a magnetic field experiences magnetic lorentz force due to which the particle moves in a circular path.

Construction

It consists of a hollow metal cylinder divided into two sections D1and D2called Dees, enclosed in an evacuated chamber (Fig 3.21). The Dees are kept separated and a source of ions is placed at the centre in the gap between the Dees. They are placed between the pole pieces of a strong electromagnet. The magnetic field acts perpendicular to the plane of the Dees. The Dees are connected to a high frequency oscillator.

Working:

When a positive ion of charge q and mass m is emitted from the source, it is accelerated towards the Dee having a negative potential at that instant of time. Due to the normal magnetic field, the ion experiences magnetic lorentz force and moves in a circular path. By the time the ion arrives at the gap between the Dees, the polarity of the Dees gets reversed. Hence the particle is once again accelerated and moves into the other Dee with a greater velocity along a circle of greater radius. Thus the particle moves in a spiral path of increasing radius and when it comes near the edge, it is taken out with the help of a deflector plate (D.P). The particle with high energy is now allowed to hit the target T.

When the particle moves along a circle of radius r with a velocityv, the magnetic Lorentz force provides the necessary centripetal force.

Bqv = (vm2) / r

v /r = Bq / m = constant ...(1)

The time taken to describe a semi-circle

t = π r / v (2)

Substituting equation (1) in (2),

t = π m/ Bq ..(3)

It is clear from equation (3) that the time taken by the ion to describe a semi-circle is independent of

(i) the radius (r) of the path and (ii) the velocity (v) of the particle

Hence, period of rotation T = 2t

T =2 π m / Bq = constant ...(4)

So, in a uniform magnetic field, the ion traverses all the circles in exactly the same time. The frequency of rotation of the particle,

v= 1 /T = Bq / 2πm ..(5)

If the high frequency oscillator is adjusted to produce oscillations of frequency as given in equation (5), resonance occurs.

Cyclotron is used to accelerate protons, deutrons and α - particles.

Incircular motion,thetimeperiodisdefinedasthetime taken bytheobject to complete one revolution onits circularpath.Its S I unitis second.The frequencyisdefinedastheno. of revolutions completed bytheobject onits circularpath in aunittime. ItSI unitis Hertz (Hz).

We have,Angular momentum = L = IωWhere, I is the moment of inertia and ω is the angular velocity.So frequency of revolution is, f = ω/2π=> ω = 2πfKinetic energy, K = ½ Iω2 = ½ Lω = ½ (2πfL) = πfL …………..(1)Now, frequency is doubled, so, let f/ = 2f = 2(ω/2π) = ω/πThe kinetic energy is halved, so, K/ = K/2 = ½ (πfL)If L/ is the new angular momentum, then using (1) we can write,K/ = πf/L/=> ½ (πfL) = π(2f)L/=> L/ = L/4So, angular momentum becomes one fourth of its original value.

l/4 is the andwer of the question

L/4is the correct answer

1/4 is the correct answer

L/4 is the correct answer

1l/4 is the correct answer