Cheat Sheet: Electricity | Science Class 10 PDF Download

 Page 1


Electricit y Cheatsheet
1 In tro duction to Electricit y
• Definition : Electricit y is a form of energy resulting from the mo v emen t of c harged
particles, suc h as e lectrons or ions.
• Origin : Deriv ed from Greek w ords “Electrica” and “Elektron. ” First observ ed b y Thales
for the attracting c apacit y of rubb ed materials.
• Applications : P o w ers homes, sc ho ols, hospitals, and industries.
2 Key Concepts
2.1 Conductors and Insulators
• Conductors : Materials allo wing free flo w of electric c harge (e.g., copp er, aluminium).
• Insulators : Materials resisting electric c harge flo w (e.g., rubb er, glass, plastic).
• Curren t Electricit y : In v olv es mo ving c harges.
• Electric Circuit : A con tin uous, closed path for electric curren t.
2.2 Electric Curren t
• Definition : Rate of flo w of electric c harge through a conductor’s cross-section.
• F orm ula : I =
Q
t
, where I is cur ren t, Q is c harge, t is time.
• SI Unit : Amp ere (A), where1 A=1 C/s.
• Con v en tional Curren t : Direction of p ositiv e c harge flo w (opp osite to electron flo w).
• Electron Flo w : Flo w of electrons constitutes curren t in conductors.
2.3 Electric P oten tial & P oten tial Difference
• Analogy : Electric c harge flo w is lik e w ater flo w in a pip e; curren t flo ws from higher to
lo w er p oten tial.
• P oten tial Difference (V) : W ork done to mo v e a unit p ositiv e c harge b et w een t w o
p oin ts.
• F orm ula : V =
W
Q
, where W is w ork done, Q is c harge.
• SI Unit : V olt (V), where1 V=1 J/C.
• Source : Main tained b y a cell or battery via c hemical action.
2
Page 2


Electricit y Cheatsheet
1 In tro duction to Electricit y
• Definition : Electricit y is a form of energy resulting from the mo v emen t of c harged
particles, suc h as e lectrons or ions.
• Origin : Deriv ed from Greek w ords “Electrica” and “Elektron. ” First observ ed b y Thales
for the attracting c apacit y of rubb ed materials.
• Applications : P o w ers homes, sc ho ols, hospitals, and industries.
2 Key Concepts
2.1 Conductors and Insulators
• Conductors : Materials allo wing free flo w of electric c harge (e.g., copp er, aluminium).
• Insulators : Materials resisting electric c harge flo w (e.g., rubb er, glass, plastic).
• Curren t Electricit y : In v olv es mo ving c harges.
• Electric Circuit : A con tin uous, closed path for electric curren t.
2.2 Electric Curren t
• Definition : Rate of flo w of electric c harge through a conductor’s cross-section.
• F orm ula : I =
Q
t
, where I is cur ren t, Q is c harge, t is time.
• SI Unit : Amp ere (A), where1 A=1 C/s.
• Con v en tional Curren t : Direction of p ositiv e c harge flo w (opp osite to electron flo w).
• Electron Flo w : Flo w of electrons constitutes curren t in conductors.
2.3 Electric P oten tial & P oten tial Difference
• Analogy : Electric c harge flo w is lik e w ater flo w in a pip e; curren t flo ws from higher to
lo w er p oten tial.
• P oten tial Difference (V) : W ork done to mo v e a unit p ositiv e c harge b et w een t w o
p oin ts.
• F orm ula : V =
W
Q
, where W is w ork done, Q is c harge.
• SI Unit : V olt (V), where1 V=1 J/C.
• Source : Main tained b y a cell or battery via c hemical action.
2
2.4 Circuit Diagram
• Definition : Simplified represen tation of an electrical circuit using standard sym b ols.
• Purp ose : Sho ws comp onen t p ositions and connections for electricians.
• Comp onen ts : Battery , resistor, ammeter, v oltmeter, switc h, wires.
2.5 Ohm’s La w
• Statemen t : A t constan t temp erature, curren t (I ) through a conductor is directly pro-
p ortional to p oten tial difference ( V ).
• F orm ula : V =I ·R , where R is resistance.
• Resistance (R) : Opp osition to curren t flo w, measured in ohms ( ? ).
• SI Unit of Resistance : 1?=
1 V
1 A
.
2.6 A ctivit y: Ohm’s La w V erification
• Ob jectiv e : Study relationship b et w een V and I in a nic hrome wire.
• Materials : Nic hrome wire, ammeter, v oltmeter, cells, wires, switc h, circuit b oard.
• Pro cedure :
1. Connect circuit with nic hrome wire, ammeter (series), v oltmeter (parallel), one cell.
2. Record I and V with switc h closed.
3. A dd cells, record I and V eac h time.
4. T abulate results; calculate
V
I
.
• Observ ation :
V
I
is constan t (R ), and V -I graph is a straigh t line through origin.
2.7 F actors Affecting Resistance
• Dep ends On :
– Length (L ): R ?L .
– Cross-sectional area (A ): R ?
1
A
.
– Material nature and temp erature.
• F orm ula : R=
?·L
A
, where ? is resistivi t y .
• Resistivit y (? ) : Resistance of a 1 m cub e with curren t p erp endicular to opp osite faces.
• SI Unit : Ohm-metre (?· m).
• V alues :
– Metals/Allo ys: Lo w resistivit y , go o d conductors.
– Insulators: High resistivit y .
• T emp erature Effect : Resistance and resistivit y increase with temp erature for metals.
3
Page 3


Electricit y Cheatsheet
1 In tro duction to Electricit y
• Definition : Electricit y is a form of energy resulting from the mo v emen t of c harged
particles, suc h as e lectrons or ions.
• Origin : Deriv ed from Greek w ords “Electrica” and “Elektron. ” First observ ed b y Thales
for the attracting c apacit y of rubb ed materials.
• Applications : P o w ers homes, sc ho ols, hospitals, and industries.
2 Key Concepts
2.1 Conductors and Insulators
• Conductors : Materials allo wing free flo w of electric c harge (e.g., copp er, aluminium).
• Insulators : Materials resisting electric c harge flo w (e.g., rubb er, glass, plastic).
• Curren t Electricit y : In v olv es mo ving c harges.
• Electric Circuit : A con tin uous, closed path for electric curren t.
2.2 Electric Curren t
• Definition : Rate of flo w of electric c harge through a conductor’s cross-section.
• F orm ula : I =
Q
t
, where I is cur ren t, Q is c harge, t is time.
• SI Unit : Amp ere (A), where1 A=1 C/s.
• Con v en tional Curren t : Direction of p ositiv e c harge flo w (opp osite to electron flo w).
• Electron Flo w : Flo w of electrons constitutes curren t in conductors.
2.3 Electric P oten tial & P oten tial Difference
• Analogy : Electric c harge flo w is lik e w ater flo w in a pip e; curren t flo ws from higher to
lo w er p oten tial.
• P oten tial Difference (V) : W ork done to mo v e a unit p ositiv e c harge b et w een t w o
p oin ts.
• F orm ula : V =
W
Q
, where W is w ork done, Q is c harge.
• SI Unit : V olt (V), where1 V=1 J/C.
• Source : Main tained b y a cell or battery via c hemical action.
2
2.4 Circuit Diagram
• Definition : Simplified represen tation of an electrical circuit using standard sym b ols.
• Purp ose : Sho ws comp onen t p ositions and connections for electricians.
• Comp onen ts : Battery , resistor, ammeter, v oltmeter, switc h, wires.
2.5 Ohm’s La w
• Statemen t : A t constan t temp erature, curren t (I ) through a conductor is directly pro-
p ortional to p oten tial difference ( V ).
• F orm ula : V =I ·R , where R is resistance.
• Resistance (R) : Opp osition to curren t flo w, measured in ohms ( ? ).
• SI Unit of Resistance : 1?=
1 V
1 A
.
2.6 A ctivit y: Ohm’s La w V erification
• Ob jectiv e : Study relationship b et w een V and I in a nic hrome wire.
• Materials : Nic hrome wire, ammeter, v oltmeter, cells, wires, switc h, circuit b oard.
• Pro cedure :
1. Connect circuit with nic hrome wire, ammeter (series), v oltmeter (parallel), one cell.
2. Record I and V with switc h closed.
3. A dd cells, record I and V eac h time.
4. T abulate results; calculate
V
I
.
• Observ ation :
V
I
is constan t (R ), and V -I graph is a straigh t line through origin.
2.7 F actors Affecting Resistance
• Dep ends On :
– Length (L ): R ?L .
– Cross-sectional area (A ): R ?
1
A
.
– Material nature and temp erature.
• F orm ula : R=
?·L
A
, where ? is resistivi t y .
• Resistivit y (? ) : Resistance of a 1 m cub e with curren t p erp endicular to opp osite faces.
• SI Unit : Ohm-metre (?· m).
• V alues :
– Metals/Allo ys: Lo w resistivit y , go o d conductors.
– Insulators: High resistivit y .
• T emp erature Effect : Resistance and resistivit y increase with temp erature for metals.
3
• Materials :
– Copp er/Aluminium: Lo w resistivit y , used in transmission lines.
– Nic hrome: Higher resistivit y , used in heaters (resists o xidation).
– T ungsten: High melting p oin t, used in bulb filamen ts.
• Devices :
– Rheostat : V ariable resistor to regulate curren t.
– Ammeter : Measures curren t in amp eres.
– V oltmeter : Measures p oten tial difference in v olts.
2.8 Resistance of System of Resistors
• Series Com bination :
– Same curren t through all resistors.
– T otal v oltage = Sum of individual v oltage drops.
– Equiv alen t resistance: R
s
=R
1
+R
2
+R
3
+... .
• P arallel Com bination :
– Same v oltage across all resistors.
– T otal curren t = Sum of individual curren ts.
– Equiv alen t resistance:
1
Rp
=
1
R
1
+
1
R
2
+
1
R
3
+... .
• Household Circuits : P arallel preferred b ecause:
– Eac h appliance dra ws required curren t.
– Indep enden t on/off switc hes.
– Lo w er total resistance, stronger curren t.
2.9 Heating Effect of Electric Curren t
• Joule’s La w : Heat pro duced: H =I
2
·R·t .
• Energy Consumed : W =V ·I ·t=I
2
·R·t=
V
2
R
·t .
• Series Circuits : Use W =I
2
·R·t (same curren t).
• P arallel Circuits : Use W =
V
2
R
·t (same v oltage).
2.10 Practical Applications of Heating Effect
• Electric Bulbs : Filamen ts (tungsten) pro duce ligh t at high temp eratures; bulbs filled
with nitrogen/argon t o prolong filamen t life.
• Electric F use : Melts at high curren t to break circuit, protecting appliances.
– Made of lo w-melting-p oin t metal/allo y , placed in series.
4
Page 4


Electricit y Cheatsheet
1 In tro duction to Electricit y
• Definition : Electricit y is a form of energy resulting from the mo v emen t of c harged
particles, suc h as e lectrons or ions.
• Origin : Deriv ed from Greek w ords “Electrica” and “Elektron. ” First observ ed b y Thales
for the attracting c apacit y of rubb ed materials.
• Applications : P o w ers homes, sc ho ols, hospitals, and industries.
2 Key Concepts
2.1 Conductors and Insulators
• Conductors : Materials allo wing free flo w of electric c harge (e.g., copp er, aluminium).
• Insulators : Materials resisting electric c harge flo w (e.g., rubb er, glass, plastic).
• Curren t Electricit y : In v olv es mo ving c harges.
• Electric Circuit : A con tin uous, closed path for electric curren t.
2.2 Electric Curren t
• Definition : Rate of flo w of electric c harge through a conductor’s cross-section.
• F orm ula : I =
Q
t
, where I is cur ren t, Q is c harge, t is time.
• SI Unit : Amp ere (A), where1 A=1 C/s.
• Con v en tional Curren t : Direction of p ositiv e c harge flo w (opp osite to electron flo w).
• Electron Flo w : Flo w of electrons constitutes curren t in conductors.
2.3 Electric P oten tial & P oten tial Difference
• Analogy : Electric c harge flo w is lik e w ater flo w in a pip e; curren t flo ws from higher to
lo w er p oten tial.
• P oten tial Difference (V) : W ork done to mo v e a unit p ositiv e c harge b et w een t w o
p oin ts.
• F orm ula : V =
W
Q
, where W is w ork done, Q is c harge.
• SI Unit : V olt (V), where1 V=1 J/C.
• Source : Main tained b y a cell or battery via c hemical action.
2
2.4 Circuit Diagram
• Definition : Simplified represen tation of an electrical circuit using standard sym b ols.
• Purp ose : Sho ws comp onen t p ositions and connections for electricians.
• Comp onen ts : Battery , resistor, ammeter, v oltmeter, switc h, wires.
2.5 Ohm’s La w
• Statemen t : A t constan t temp erature, curren t (I ) through a conductor is directly pro-
p ortional to p oten tial difference ( V ).
• F orm ula : V =I ·R , where R is resistance.
• Resistance (R) : Opp osition to curren t flo w, measured in ohms ( ? ).
• SI Unit of Resistance : 1?=
1 V
1 A
.
2.6 A ctivit y: Ohm’s La w V erification
• Ob jectiv e : Study relationship b et w een V and I in a nic hrome wire.
• Materials : Nic hrome wire, ammeter, v oltmeter, cells, wires, switc h, circuit b oard.
• Pro cedure :
1. Connect circuit with nic hrome wire, ammeter (series), v oltmeter (parallel), one cell.
2. Record I and V with switc h closed.
3. A dd cells, record I and V eac h time.
4. T abulate results; calculate
V
I
.
• Observ ation :
V
I
is constan t (R ), and V -I graph is a straigh t line through origin.
2.7 F actors Affecting Resistance
• Dep ends On :
– Length (L ): R ?L .
– Cross-sectional area (A ): R ?
1
A
.
– Material nature and temp erature.
• F orm ula : R=
?·L
A
, where ? is resistivi t y .
• Resistivit y (? ) : Resistance of a 1 m cub e with curren t p erp endicular to opp osite faces.
• SI Unit : Ohm-metre (?· m).
• V alues :
– Metals/Allo ys: Lo w resistivit y , go o d conductors.
– Insulators: High resistivit y .
• T emp erature Effect : Resistance and resistivit y increase with temp erature for metals.
3
• Materials :
– Copp er/Aluminium: Lo w resistivit y , used in transmission lines.
– Nic hrome: Higher resistivit y , used in heaters (resists o xidation).
– T ungsten: High melting p oin t, used in bulb filamen ts.
• Devices :
– Rheostat : V ariable resistor to regulate curren t.
– Ammeter : Measures curren t in amp eres.
– V oltmeter : Measures p oten tial difference in v olts.
2.8 Resistance of System of Resistors
• Series Com bination :
– Same curren t through all resistors.
– T otal v oltage = Sum of individual v oltage drops.
– Equiv alen t resistance: R
s
=R
1
+R
2
+R
3
+... .
• P arallel Com bination :
– Same v oltage across all resistors.
– T otal curren t = Sum of individual curren ts.
– Equiv alen t resistance:
1
Rp
=
1
R
1
+
1
R
2
+
1
R
3
+... .
• Household Circuits : P arallel preferred b ecause:
– Eac h appliance dra ws required curren t.
– Indep enden t on/off switc hes.
– Lo w er total resistance, stronger curren t.
2.9 Heating Effect of Electric Curren t
• Joule’s La w : Heat pro duced: H =I
2
·R·t .
• Energy Consumed : W =V ·I ·t=I
2
·R·t=
V
2
R
·t .
• Series Circuits : Use W =I
2
·R·t (same curren t).
• P arallel Circuits : Use W =
V
2
R
·t (same v oltage).
2.10 Practical Applications of Heating Effect
• Electric Bulbs : Filamen ts (tungsten) pro duce ligh t at high temp eratures; bulbs filled
with nitrogen/argon t o prolong filamen t life.
• Electric F use : Melts at high curren t to break circuit, protecting appliances.
– Made of lo w-melting-p oin t metal/allo y , placed in series.
4
2.11 Electric P o w er
• Definition : Rate of doing electric w ork.
• F orm ula : P =V ·I =I
2
·R=
V
2
R
.
• SI Unit : W att (W), where1 W=1 V· A.
• Commercial Unit : Kilo w att-hour (k Wh).
5