Question

If an electric bulb has a rating 200 watt, 220 volt and if it is used for 5 hours daily for 10 days, calculate the cost of using the bulb at 40
paise per kWh.​

Answer 1

ɢɪᴠᴇɴ :-

• Rating of electric bulb = 200 W,220 V
• Time for which bulb is daily used, t = 5 hrs
• No. of days for which bulb is used = 10 days
• Rate of consuming per kWh energy = 40 Paise

ᴛᴏ ғɪɴᴅ :-

• Cost of using the bulb

ᴋɴᴏᴡʟᴇᴅɢᴇ ʀᴇǫᴜɪʀᴇᴅ :-

• E = P × t

(where, E is the electrical energy (in Watt - hour unit) , P is the Power (in Watt unit) and t is the time (in Hours))

sᴏʟᴜᴛɪᴏɴ :-

Using formula

➥ E = P × t

Calculating Energy consumed daily by the bulb

putting known values

➥ E = 200 W × 5 h

➥ E = 1000 Wh

since, 1 kWh = 1000 Wh

therefore,

➥ E = 1 kWh

Calculating total energy consumed by bulb in 10 days

➥ Total Energy consumed = 10 × 1 kWh

➥ Total energy consumed = 10 kWh

Now,

Calculating Cost of using bulb at 40 paise per kWh

➦ Total cost of using bulb = 40 × 10

➦ Total cost of using bulb = 400 Paise

Converting into Rupees

➦ Total cost of using bulb = 4 Rs (Ans.)