Current - part 2

Question 1

In a electric cell chemical energy changes to ______

Answer 1

electrical

Question 2

what is emf?
emf denoted by ?
emf formula?-work ,charge
emf measured by \_\_\_\_\_\_\_
emf not dependent on \_\_\_\_\_\_\_\_

Answer 2

when no current is drawn from the cell , the potential difference between the terminals
e.m.f → denoted by epsilon
E=W/Q
Epsilon unit → Volt → measured by connecting voltmeter of high resistance
Not dependent on → shape of electrode , distance between two electrode , amount of electrolyte used

Question 3

FACTORS AFFECTING EMF

Answer 3

Factors affecting e.m.f of a cell

• Material of the electrode
• Electrolyte used in a cell

Question 4

Terminal voltage means 
terminal voltage denoted by 
terminal voltage formula
relationship  between terminal voltage and emf
voltage drop means 
voltage drop formula

Answer 4

As a work done in moving a positive test charge across the terminals [ outside the circuit not inside]
denoted by V → expressed in Volt
V=w/q
Terminal voltage → when current is drawn from the cell , when cell is in closed circuit → the potential difference between the electrodes .
Terminal voltage is less than emf
Voltage drop → work done per unit charge in carrying positive test charge through the electrolyte of the cell .
v=w/q

Question 5

Relationship between Terminal voltage and emf –>

Answer 5

e → epsilon , V→ terminal voltage , v → voltage drop

e= V + v

When cell is not in use → Emf = Terminal voltage

Emf → does not depend on amount of current drawn from the cell

terminal voltage → depends on the amount of current drawn from the cell

When the cell is in use → Emf > terminal voltage

Question 6

What is mean by internal resistance?

Answer 6

Internal Resistance → The resistance offered by electrolyte inside the cell to the flow of current

Internal Resistance → denoted by symbol r → unit ohm

Question 7

voltage drop formula
Current formula
Terminal voltage formula
Internal resistance formula

Answer 7

v= Ir

I = emf / total resistance

V = IR

r=[E/V -1]R

Question 8

Factors affecting Internal resistance -

Answer 8

• Surface area of electrode → more surface area - less r
• Distance between the electrodes → more distance between electrode - greater r
• Nature and concentration of electrolyte → less ionic or higher concentration of electrolyte - more r
• Temperature of electrolyte → higher the temp - less r

Question 9

Combination of resistors in series

Answer 9

The series following Two facts

• Potential difference is directly proportional to its resistance , potential difference is different across different resistance
• Potential difference across the entire circuit = to sum of potential difference across each resistors

V= V1 + V2 + V3 …

Total resistance = sum of individual resistance

Question 10

Combination of resistor

Answer 10

V= V1=V2=V3

Potential difference is same Because they have same starting and ending point .

I is divided

Equivalent resistance → 1/rp = 1/r1 + 1/r2 + 1/r3

For two resistors joined in series , the Equivalent is more then when they are joined in parallel