Class 12 Physics — Chapter 1:
Electric Charges and Fields
CBSE Board Notes with Numericals
1. Electric Charge
Charge ek intrinsic property hai jiski wajah se
particle electric aur magnetic force experience
karta hai.
Do prakar ke charge: positive aur negative.
Like charges repel, unlike charges attract.
SI unit: Coulomb (C)
Properties of Charge
1. Additivity — charges simply algebraically add
(scalar-like addition): Q = q1 + q2 + q3 + ...
2. Conservation of charge — total charge of an
isolated system hamesha constant rehta hai
(charge na banta hai na nasht hota hai, sirf
transfer hota hai).
, 3. Quantization of charge — charge hamesha
integral multiple of e (elementary charge) mein
milta hai:
$$q = ne, \quad n = 0, \pm1, \pm2,...$$
jahan e = 1.6 × 10⁻¹⁹ C
2. Conductors and Insulators
Conductors: free electrons hote hain jo easily
move kar sakte hain (metals). Charge poora
surface pe distribute ho jata hai.
Insulators (Dielectrics): free charge carriers nahi
hote, charge apni jagah pe hi rehta hai.
Charging Methods
1. Friction — rubbing se
2. Conduction — charged body ko touch karke
3. Induction — bina touch kiye, opposite charge
induce karna
3. Coulomb's Law
Do point charges ke beech force:
$$F = \frac{1}{4\pi\varepsilon_0} \cdot \frac{q_1 q_2}
{r^2}$$
Electric Charges and Fields
CBSE Board Notes with Numericals
1. Electric Charge
Charge ek intrinsic property hai jiski wajah se
particle electric aur magnetic force experience
karta hai.
Do prakar ke charge: positive aur negative.
Like charges repel, unlike charges attract.
SI unit: Coulomb (C)
Properties of Charge
1. Additivity — charges simply algebraically add
(scalar-like addition): Q = q1 + q2 + q3 + ...
2. Conservation of charge — total charge of an
isolated system hamesha constant rehta hai
(charge na banta hai na nasht hota hai, sirf
transfer hota hai).
, 3. Quantization of charge — charge hamesha
integral multiple of e (elementary charge) mein
milta hai:
$$q = ne, \quad n = 0, \pm1, \pm2,...$$
jahan e = 1.6 × 10⁻¹⁹ C
2. Conductors and Insulators
Conductors: free electrons hote hain jo easily
move kar sakte hain (metals). Charge poora
surface pe distribute ho jata hai.
Insulators (Dielectrics): free charge carriers nahi
hote, charge apni jagah pe hi rehta hai.
Charging Methods
1. Friction — rubbing se
2. Conduction — charged body ko touch karke
3. Induction — bina touch kiye, opposite charge
induce karna
3. Coulomb's Law
Do point charges ke beech force:
$$F = \frac{1}{4\pi\varepsilon_0} \cdot \frac{q_1 q_2}
{r^2}$$
