Tag: physics

Questions Related to physics

Which of the following scientists did the pioneering work to understand the splitting of white light in different components ?

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Thomas Edison

  2. Albert Einstein

  3. Issac Newton

  4. Archimedes

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Correct Option: C
Explanation:

Newton was the first to understand that white light consists of a mix of light rays, each with a different colour.

The spreading of white light into its component colours is known as.

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Dispersion

  2. Deviation

  3. Refraction

  4. Diffraction

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Correct Option: A
Explanation:

$\text{Defination of Dispersion :-}$

Dispersion is the phenomenon of spreading of white light into its component colors. 

A thermistor:

physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. Is a thermally sensitive resistor

  2. Is made of a semiconductor

  3. Has negative temperature coefficient of resistance

  4. All the above

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Correct Option: D
Explanation:
A thermistor is a type of resistor whose resistance depends on temperature, more than in standard resistor. The word is a combination of thermal and resistor. They are widely used as inrush current limiters, temperature sensors, self -resetting overcurrent protectors, and self-regulating heating elements.
It is made up of semiconductors and has a negative temperature coefficient of resistance.

Thermistor has a resistance of ________

physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. 250 to 500 k ohms

  2. 50 to 10 k ohms

  3. 1 to 1 k ohms

  4. 100 to 100 k ohms

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Correct Option: D
Explanation:

Thermistor has a resistance range of 100 to 100 k. Thermistor consists of a mixture of metallic oxides of manganese, nickel, cobalt, copper, iron and uranium.

Thermistor material is pressed ________

physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. under zero pressure

  2. under low pressure

  3. under high pressure

  4. under low volume

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Correct Option: C
Explanation:

A thermistor material is usually pressed under high pressure to form a flat cylindrical shape. Disks and washers are placed in series or in parallel to increase the power dissipation.

Thermistors have ________

physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. positive temperature coefficient

  2. negative temperature coefficient

  3. zero temperature coefficien

  4. infinite temperature coefficient

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Correct Option: B
Explanation:

Thermistor generally has a negative temperature coefficient of resistance. With increase in temperature, resistance of a thermistor decreases.

Thermistor follows which law for small variations ________

physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. Charles law

  2. KVL

  3. KCL

  4. Ohms law

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Correct Option: D
Explanation:

For small changes in the values of current, voltage across a thermistor increases. It attains a peak value. Then the voltage across the thermistor decreases. As a result Ohms law is followed at small variations of current.

Which of the following is/are correct?

physics magnetic effect of electric current oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. Electric current can produce a magnetism

  2. Due to change in current the magnetic strength changes

  3. Magnetic strength of a magnet is independent of the number of turn in the current carrying coil

  4. All of the above

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Correct Option: D
Explanation:

I)According to Oersted experiment electric current can produce magnetism.

iI)Magnetic induction $B \alpha I$
If current changes the strength $B$ changes.
iiI)For circular coil magnetic field $B$ due to single ring $B=\dfrac{\mu _0 i}{2r}$
If magnet contain n turn then its strength is $B _2=nB$
But if current carrying coil have $n _2$ turn then strength doesn't change.
$B _2=nB$
Hence all options are correct.

A compass needle placed at a distance $r$ from a short magnet in $\tan\ A$ position shown a deflection of $60^{o}$. If the distance is increased to $r(3)^{1/3}$, then the deflected of the compass needle is:

physics magnetic effect of electric current oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. $30^{o}$

  2. $60^{o}\ \times (3)^{1/3}$

  3. $60^{o}\ \times (3)^{2/3}$

  4. $90^{o}\ \times (3)^{1/3}$

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Correct Option: A

Electromagnet can be formed due to which of the following?

physics magnetic effect of electric current oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. Heating effect of current

  2. Magnetic effect of current

  3. Chemical effect of current

  4. None of the above

Show answer
Correct Option: B
Explanation:

Electromagnets are formed by passing an electric current through a wire coiled around the substance with iron core. The electric current generates a magnetic field around the  substance and thus magnetize it which convert it into a magnet. Thus electromagnet can be formed due to the magnetic effect of current.