## Scenario 2: Charging A Power Bank

###### System: Power bank

###### Initial State: A power bank at 50% of its maximum capacity was connected to the electrical mains.

###### Final State: The power bank was fully charged and it became warm.

###### Remarks: Assume no energy was transferred from the power bank to the surroundings by heating.

Hint 1
Consider the principle of conservation of energy.
Hint 2
Consider the type of energy transfer when the battery is connected to the electrical mains.

##### Initial Amount of Energy of the System

##### System

##### Final Amount of Energy of the System

Energy / Units

C
E
G
I
K
N

Energy Transfer In:
Type Of Transfer
Propagation of waves Propagation of waves
Heating Heating
Electrically Electrically
Mechanically Mechanically
------------ ------------
Type Of Transfer
Propagation of waves Propagation of waves
Heating Heating
Electrically Electrically
Mechanically Mechanically
------------ ------------
Energy Transfer Out:
Type Of Transfer
Propagation of waves Propagation of waves
Heating Heating
Electrically Electrically
Mechanically Mechanically
------------ ------------
Type Of Transfer
Propagation of waves Propagation of waves
Heating Heating
Electrically Electrically
Mechanically Mechanically
------------ ------------

Energy / Units

C
E
G
I
K
N

##### Initial Energy of the System

+

##### Energy Transferred Into the System

=

##### Energy Transferred Out of the System

+

##### Final Energy of the System

Legend:

Electrically

Heating

C - Chemical
E - Elastic
G - Gravitational
I - Internal
K - Kinetic
N - Nuclear

Mechanically

Propagation of waves