CBSE > Class 12 > Physics | CBSE Board | Homework Help

Current flow basically means the flow of electric charges with respect to time. In an electric circuit, when the electric charge is flowing in one direction, the current will flow in the opposite direction.

The electric current flow starts from the negative terminal to the positive terminal of a battery, as the electron will flow from the positive terminal to the negative terminal.

From Ohm's law, the expression for the current is V=IR

Here, V is the voltage of the battery, R is the resistance connected in the circuit, and I is the current flow in the circuit.

From Ohm's law, the current can be defined as the voltage through the circuit per unit resistance.

The unit of current is Ampere (A).

When the current flows through the circuit, it causes heating in that device; as a result, we can get light in an incandescent light bulb. This heating is known as Joule heating.

Current is of two types:

• DC current, which is created from a Dc voltage source

• AC Current, which is created from an Ac voltage source

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Unite of vector

Posted by Tadak Nilling 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Gaurav Seth 6 years, 11 months ago

A unit vector simply denotes the direction. If we have a vector 4i + 3j. I will use a 2D vector because it is easier to understand.

The magnitude of this vector is 5 units.

The unit vector will be 0.8i + 0.6j.

When you plot this unit vector on a graph paper. Along x axis, go 0.8 units. From this point, go up 0.6 units parallel to the y axis. The resultant will be 1 (the hypotenuse length).

If the value 5 is multiplies with this unit vector, it simply means that you produce the same effect of the vector 4i + 3j. with the vector 5 times 0.8i + 0.6j.

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Define ohm's law

Posted by Hillang Sumpa 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Gaurav Seth 6 years, 11 months ago

Ohm’s Law: The electric current flowing through a conductor wire is directly proportional to the voltage difference across the conductor wires if there is no change in the conditions such as, temperature, length, area of cross section etc. of the wire.

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Nenh=ni2

Posted by Shaswat Pandey 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Utsav Aryan 6 years, 11 months ago

Intrinsic semiconductors

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how can output characteristics be used to obtain current gain.in transistor

Posted by Abha Rl 6 years, 11 months ago

CBSE > Class 12 > Physics

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Why photodiode is reverse biased?

Posted by Lishma Sahu 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Atufa Bi 6 years, 11 months ago

fractional increase in majority charge carriers is much less than fractional increase in minority charge carriers therefore photo diode is reversed biased for measuring light intensity

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mountain D drr ke aagye jit hai pii kr Jna Sabhi log physics kr liye

Posted by Sachin Kumar Yadav 6 years, 11 months ago

CBSE > Class 12 > Physics

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imp topic of wave optics

Posted by Rakesh Tiwari 6 years, 11 months ago

CBSE > Class 12 > Physics

2 answers

Atufa Bi 6 years, 11 months ago

interferance ydse

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Dhruv Bansal 6 years, 11 months ago

condition for constructive and destructive interference fringe width

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What is digital signal

Posted by Harsh Singh Singh 6 years, 11 months ago

CBSE > Class 12 > Physics

2 answers

Atufa Bi 6 years, 11 months ago

the signals which do not vary with tym and have only two binary values ie 1 and 0

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Dhruv Bansal 6 years, 11 months ago

also called pulse signals

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State the basic model of communication

Posted by Yaman Kumar 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Dhruv Bansal 6 years, 11 months ago

point to point (telephony) broad cast

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Why it is necessary that a field line from a point charge placed in the vincity of a conductor must be normal to the surface of conductor at every point?

Posted by Muskan Sindhu 6 years, 11 months ago

CBSE > Class 12 > Physics

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At any point on axis or tanA postion

Posted by Sanjay Dhali 6 years, 11 months ago

CBSE > Class 12 > Physics

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The half life of radioactive substance is 30 s calculate Time taken for the sample to decay 3/4 th of the intial value

Posted by Kumar Sanskar 6 years, 11 months ago

CBSE > Class 12 > Physics

0 answers

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Two long and parallel straight carrying currents of 2A and 5A in the opposite direction ate separated by a distance of 1cm. Find the nature and magnitude of the magnet ic field between equilateral triangular prism of refracting angle A trace the path

Posted by Ýashwanť Banger 6 years, 11 months ago

CBSE > Class 12 > Physics

0 answers

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Derivation of energy stored in a capacitor

Posted by Priyanka Paul 6 years, 11 months ago

CBSE > Class 12 > Physics

0 answers

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State the basic modes of communication

Posted by Ravi Yadav 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Priyanka Paul 6 years, 11 months ago

Point to point communication : The communication takes place over a link between a single transmitter nd receiver. Ex: Telephony. Broadcast mode: In such a mode, large no. Of receivers is linked to a single transmitter. Ex: radio

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Which Chapter has Max. Marks waightage

Posted by Rakesh Tiwari 6 years, 11 months ago

CBSE > Class 12 > Physics

2 answers

Priyanka Paul 6 years, 11 months ago

Electrostatic - 9 Current electricity - 6 Magnetic effects of current - 9 Em induction & AC - 6 Em wave - 2 Optics - 14 Dual nature of matter nd radiation - 5 Atoms , nuclei nd radioactivity - 9 Electronic devices - 6 Communication system - 4

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Sahana Sankaranarayanan 6 years, 11 months ago

Optics unit together

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An electric dipole of length 4cm,when placed with its axis making an angle of 60 0 with a uniform electric field experiences a torque of 4√3 Nm.Calculate the magnitude of electric field,if the dipole has charges 8uC and -8uC.

Posted by Shubham Patidar 6 years, 11 months ago

CBSE > Class 12 > Physics

0 answers

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What is parallex method?

Posted by Nitin Ahlawat 6 years, 11 months ago

CBSE > Class 12 > Physics

0 answers

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Wahat is theorem of Gauss law and there application?

Posted by Yuvraj Sahu 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Nivetha Vijayakumar 6 years, 11 months ago

Gauss law: the surface integral of electric field intensity over any closed surface in free space is equal to 1/€0 times the net charge eclosed by the surface. Applications: E for infinitely long wire, E= 2k * lamda /r E for thin charged sheet, E = sigma / 2€0

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Define electric intensity. State its unit and dimension.

Posted by Anit Singh 6 years, 11 months ago

CBSE > Class 12 > Physics

1 answers

Priyanka Paul 6 years, 11 months ago

The electric field inteny at any point due to source charge is defined as the force experienced per unit positive test charge placed at that point without disturbing the source charge. It is expressed as Vector E =lim qtends to 0 vector F/ q0 Here q0 tends to 0 i.e, test charge q0 must be small, so that it does not produce its own electric field. Si unit of electric field intensity (E) is N/C and it is a vector quantity.

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Two radioactive nuclei X and Y initially contain eauation number of atom

Posted by Shubham Sharma 6 years, 11 months ago

CBSE > Class 12 > Physics