Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics chemical effects of electric current does liquid conduct electricity? liquids conduct electricity do liquids conduct electricity?

Most liquids that conduct electricity are solutions of :

  1. acids

  2. bases

  3. salts

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Most liquids that conduct electricity are solutions of acids, bases ,and salts (because the  solutions of acids, bases or salts are conducting in nature. They allow the current to pass through

Multiple choice physics chemical effects of electric current does liquid conduct electricity? liquids conduct electricity do liquids conduct electricity?

Water obtained from which of the following sources is a good conductor of electricity?

  1. Tap

  2. Ponds

  3. Wells

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The water that we get from sources such as taps, hand pumps, wells and ponds is not pure. It may contain several salts dissolved in it. Small amounts of mineral salts are naturally present in it. This water is thus a good conductor of electricity.

Multiple choice physics chemical effects of electric current does liquid conduct electricity? liquids conduct electricity do liquids conduct electricity?

Which of the following is a good conductor of electricity?

  1. Sugar solution

  2. Oil

  3. Distilled water

  4. Tap water
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The water that we get from sources such as taps, hand pumps, wells and ponds is not pure. It may contain several salts dissolved in it. Small amounts of mineral salts are naturally present in it. This water is thus a good conductor of electricity.

Multiple choice torque on a dipole in a uniform electric field electric dipole electric charges and fields electrostatics physics

An electric dipole of moment $ \vec { p } $ is placed in a uniform electric field$\vec { E }$ . Then
(i) The torque on the dipole is $\vec { p } \times \vec { E } $.
(ii) The potential energy of the system is $\vec { p } \cdot \vec { E } $.
(iii) The resultant force on the dipole is zero.
Choose the correct option.

  1. (i), (ii) and (iii) are correct

  2. (i) and (iii) are correct and (ii) is wrong

  3. Only (i) is wrong

  4. (i) and (ii) are correct and (iii) is wrong
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a uniform electric field, $\vec { E } $, dipole experiences a torque $\vec { \tau  } $ given by $\vec { \tau  } =\vec { p } \times \vec { E } $ but experiences no force. The potential energy of the dipole in a uniform electric field $\vec { E } $ is $U=-\vec { p } .\vec { E } $

Multiple choice torque on a dipole in a uniform electric field electric dipole electric charges and fields electrostatics physics

An electric dipole of length 20 cm having $\pm3 \times { 10 }^{ -3 }$ C charge placed at 60 with respect to a uniform electric field experiences a torque of magnitude 6 N m. the potential energy of the dipole is:

  1. -2$\sqrt { 3 }$ J
  2. 5$\sqrt { 3 }$ J
  3. -3$\sqrt { 2 }$ J
  4. 3$\sqrt { 5 }$ J
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Here,

Length of dipole $2a= 20\ cm=0.2\ m$
Charge, $q= \pm 3\times 10^{-3}\ C$,             $\theta=60^o$
Torque, $\tau=6\ Nm$
As, $\tau=pEsin\ \theta$
or $E=\dfrac{\tau}{psin \theta}= \dfrac{\tau}{q(2a)sin \theta}(\because p=q(2a)$

$\therefore E=\dfrac{6}{3\times 10^{-3}\times 20 \times 10^{-2} \times sin\ 60^o}= \dfrac{10^5}{5\sqrt 3} NC^{-1}$

Potential energy of dipole, $U=-pEcos \theta=-q(2a) E cos \theta $

$\implies U= -3\times 10^{-3}(20 \times 10^{-2} )\dfrac{10^5}{5\sqrt 3} cos 60^o= -2\sqrt 3\ J$