CBSE Class 12 (Science) Electric Charges and Fields — practice questions
87 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE Class 12 (Science) Electric Charges and Fields in the app →The smallest charge that can exist freely in nature isAn electric dipole of dipole moment $\vec{p}$ is placed in a UNIFORM electric field $\vec{E}$. The torque expeThe electric field at a distance $r$ from a POINT charge $q$ (in vacuum) has magnitudeTwo charges of the same kind brought together will:Two charges of opposite kinds brought together will:A charged body far smaller than the distances involved is treated as a:For a point charge, all the charge is assumed concentrated at:Charges in a system are combined by adding them:Electric charges add up in the same way as:Charge is like mass in having magnitude but no:Unlike mass, an electric charge may also be:Conservation of charge has been established by:All free charges are integral multiples of a basic unit written:The basic unit of charge is the charge carried by a proton or:By convention, the charge on an electron is taken as:Charge coming only in whole multiples of e is called:Quantisation of charge was first suggested by the laws of:Quantisation of charge was demonstrated experimentally by:Millikan demonstrated the quantisation of charge in the year:The SI unit of electric charge is the:One coulomb is the charge flowing in one second at a current of:Coulomb measured the force between charges using a balance that is:The torsion balance was later used to measure gravity by:Touching a charged sphere to an identical uncharged one leaves each:Adding the forces from several charges one by one uses the principle of:The discovery that rubbed amber attracts light objects is credited to:The word electricity comes from the Greek word elektron, meaning:Thales of Miletus made his observation about amber around:A metal rod held in the hand and rubbed with wool shows:A neutral pith ball joined by copper wire to a negative rod acquires a charge that is:Substances that let electricity pass through them easily are called:Conductors contain electrons that are comparatively:Which of these is listed as a conductor?Glass, porcelain, plastic and wood are examples of:Charge transferred to a conductor readily gets:Charge placed on an insulator:The effects of positive and negative charge tend to:Charged bodies much smaller than their separation are treated as:Charges add up like:Charge has magnitude but no:Unlike charge, the mass of a body is always:The total charge of a system with charges +1, +2, -3, +4 and -5 units is:When two bodies are rubbed, what one body gains in charge the other:The total charge of an isolated system is always:When a neutron turns into a proton and an electron, the total charge is:Free charges come in integral multiples of a basic unit written as:Coulomb found the force between two point charges varies inversely as the:What is the magnitude of the charge on one electron?Who introduced the names positive and negative for the two kinds of charge?When a glass rod is rubbed with silk, which charge transfer takes place?By convention, which of these carries a positive charge after rubbing?What is the approximate value of the Coulomb constant k in SI units?What is the experimental value of the permittivity of free space ε0?The ratio of electric to gravitational force between a proton and an electron is about what?What does the net force on one charge due to several others equal?If the distance between two point charges is doubled, the Coulomb force becomes what fraction?If the distance between two charges becomes three times, the force changes by what factor?How is the electric field at a point defined?Which is the SI unit of electric field?A point charge of 4 μC sets up what field at 3 m from it in vacuum?What is the direction of the field due to a negative point charge?At any point on a field line, the tangent gives what?Where are electric field lines drawn closest together?What do field lines look like in a region of constant electric field?An electric dipole consists of what?What is the magnitude of the dipole moment for charges ±q separated by 2a?Charges of +3 μC and –3 μC are 2 cm apart. What is the dipole moment?Which way does the dipole moment vector point?At large distance r, how does a dipole's electric field fall off?At the same large distance, the axial field of a dipole is how many times its equatorial field?What is the equatorial plane of a dipole?A dipole in a uniform electric field experiences what?By Gauss's law, flux through a closed surface equals what?A closed surface encloses 8.854 μC in vacuum. What is the net flux through it?For a closed surface, which way is the area vector taken?How does the field of a long straight charged wire depend on distance r?An infinite thin plane sheet has uniform surface charge density σ. What is the field magnitude?What is the electric field at points inside a uniformly charged thin spherical shell?A shell of radius R has surface charge density σ. What is its total charge?Which carriers are mobile in metals?Additivity of charge means the total charge of a system is what?What does conservation of charge say about an isolated system?Quantisation of charge means any charge is what?Why can quantisation of charge be ignored for everyday objects?What is the charge on 5 × 1010 electrons?Roughly how many electrons together carry one coulomb of charge?One coulomb is the charge flowing through a wire in 1 s when the current is what?