electric charges Flashcards
The name electricity is coined from Greek word and its meaning
elektron, amber
Electric charges acquire an electric charge on
Rubbing
What are the two kinds of electrification ?
like charges repel ; unlike charges attract
Define polarity of charges
The property which differentiates the two kinds of charges
What effect does unlike charges acquired by the objects have ?
neutralize or nullify each others effect
charges were named +ve and -ve by which person ?
american scientist benjamin franklin
what is the apparatus to detect charge on a body ? describe it
gold leaf electroscope.
it consists of vertical metal rod housed in a box with two thin gold leaves attached to its bottom end. when charge object touches metal knob at top of rod, charge flows on to leaves and they diverge
degree of divergence is indicator of what ?
amount of charge
substances which allow free movement of electrons ?
conductors
substances which offer high resistance to the passage of electricity through them
insulators
The attraction is the real proof of an object being charged. true or false
false.
If an object is attracted by another charged body, the first object may be oppositely charged or not charged because we know both an uncharged object and an oppositely charged object are attracted by another charged object.
if system contains n charges of q1, q2, q3…qn the total charge of system
q1+q2+q3+q4….+qn
name the one difference between charge and mass
mass of a body is always +ve while charge of a body can be +ve, -ve
total charge of isolated system is always
CONSERVED!!!!
PONDER ON QUESTION:
fact: it is not possible to create or destroy net charge carried by isolated system although charge carrying particles may be created or destroyed
like when a neutron gets changed into proton or electron
unit of charge and value of basic unit of charge
coulomb,
1.6 * 10^-19 C
If an object is positively charged, theoretically the mass of the object
Decreases slightly by a factor of 9.1110^-31 kg.
If an object is positively charged it loses some of its electrons. The mass of an electron is 9.1110^-31 kg. So, if a positively charged body loses ‘n’ number of electrons, it mass decreases slightly by a factor of 9.11*10^-31 kg
Why is gold used in the Gold-leaf electroscope?
Gold is malleable.
Though gold is a costly metal it is used in electroscope because of the property malleability. This means very thin and light sheets can be formed from gold simply by hammering or rolling and hence the deflection of the light gold plates increases.
What happens to the plates of the apparatus if we measure alternating charge using a Gold-leaf oscilloscope?
The plates give a proper divergence.
The divergence of the plates of the Gold-leaf oscilloscope depends only on the presence of a charge, not on the quality of charge i.e. positive or negative. So, if the charge changes from positive to negative and vice versa the degree of divergence of the plates remains the same
Dr. Gilbert tried to hold a brass rod by hand and induce static electricity in it by friction. Why did he fail?
The induced static charge flew through his hand and body to the ground.
The human body is a good conductor and hence the charge produced by friction flew through his body to the ground. We can tackle the problem simply by holding the brass rod with the help of some insulated holder
