Q. 2. Rewrite the following statements selecting the correct options :
(1) The potential difference between the two electrodes of the lead-acid cell is nearly
(a) 1 V (b) 1.2 V (c) 1.5 V (d) 2 V
(2) The Ni-Cd cell delivers a potential difference of ...
(a) 1 V (b) 1.2 V (c) 1.5 V (d) 2 V
(3)
is a scalar quantity.
(a) Force (b) Acceleration (c) Velocity (d) Electric current
Answers
Answer:
The answer is YES. Lead-acid is the oldest rechargeable battery in existence. Invented by the French physician Gaston Planté in 1859, lead-acid was the first rechargeable battery for commercial use. 150 years later, we still have no cost-effective alternatives for cars, wheelchairs, scooters, golf carts and UPS systems. The lead-acid battery has retained a market share in applications where newer battery chemistries would either be too expensive.
Lead-acid does not lend itself to fast charging. Typical charge time is 8 to 16 hours. A periodic fully saturated charge is essential to prevent sulfation and the battery must always be stored in a charged state. Leaving the battery in a discharged condition causes sulfation and a recharge may not be possible.
Finding the ideal charge voltage limit is critical. A high voltage (above 2.40V/cell) produces good battery performance but shortens the service life due to grid corrosion on the positive plate. A low voltage limit is subject to sulfation on the negative plate. Leaving the battery on float charge for a prolonged time does not cause damage.
Lead-acid does not like deep cycling. A full discharge causes extra strain and each cycle robs the battery of some service life. This wear-down characteristic also applies to other battery chemistries in varying degrees. To prevent the battery from being stressed through repetitive deep discharge, a larger battery is recommended. Lead-acid is inexpensive but the operational costs can be higher than a nickel-based system if repetitive full cycles are required.
Depending on the depth of discharge and operating temperature, the sealed lead-acid provides 200 to 300 discharge/charge cycles. The primary reason for its relatively short cycle life is grid corrosion of the positive electrode, depletion of the active material and expansion of the positive plates. These changes are most prevalent at higher operating temperatures. Cycling does not prevent or reverse the trend.
The lead-acid battery has one of the lowest energy densities, making it unsuitable for portable devices. In addition, the performance at low temperatures is marginal. The self-discharge is about 40% per year, one of the best on rechargeable batteries. In comparison, nickel-cadmium self-discharges this amount in three months. The high lead content makes the lead-acid environmentally unfriendly
Answer:
1. 2v
2. 1.2
3. electric current