The star of India's most popular television show knew she had hit a national nerve when 500 angry taxi drivers protested outside the network offices demanding an apology for being portrayed as "bad characters."

Now her appearance literally causes riots in the streets. School children ring her doorbell for autographs. Everybody wants her to preside over festivals, banquets, or even the opening of new roadside stands selling fresh sugar-cane juice. "Sugar-cane stands," she says, exasperated. "Imagine." But what can she do? Even Prime Minister Rajiv Gandhi is a fan.

Since its first episode in May, the show "Rajani," on the government-owned Doordarshan network, has seized India's 50 million television viewers in a way that even its creators never imagined. Its star character, a young, feisty and great-looking middle-class housewife named Rajani, has become a new national heroine.

As people cheer in front of their television sets each Sunday morning, Rajani takes on the daily injustices that plague modern Indian life. She has gone after fake astrologers, bribe-demanding cooking-gas delivery men and pickpockets on buses.

In one episode, when a rude taxi driver refuses to take her on a short fare, she goes outraged to the police -- immediately prompting the protest of the real-life cabbies. In another, she discovers that her maid's husband is beating her, and that he is planning to take a second wife. Rajani bullies the husband to his senses. In a recent episode, when the police refuse to do anything about the noise coming from the loudspeakers at a Hindu wedding, Rajani gets her own loudspeaker and aims it straight at the station. The police give in, and Rajani wins once again.

"This is the first time there is a character voicing the problems of the middle class," says Priya Tendulkar, the 25-year-old actress who plays Rajani.

The show is in Hindi, but the phrase "doing a Rajani" has entered the Indian lexicon. During a televised tour of the south Indian state of Kerala, Rajiv Gandhi dispensed with the usual platitudes and actually asked tough questions about the plight of homeless fishermen. "Rajiv Does a Rajani" one newspaper headline enthused.

But critics complain that the show could use a lot of work. Rajani has no sense of humor, and spends most of each half-hour show haranguing bureaucrats in long soliloquies. Amita Malik, the influential television columnist for the Indian Express newspaper, dismisses the acting as "a little crude" and "monotonous."

The success of the show is in fact more a reflection of the expectations of change in Rajiv Gandhi's new India, and of a growing, consumer-oriented middle class tired of the institutional corruption that seems as entrenched in India as poverty and overpopulation.

"Indians have gotten so used to bureaucrats bullying them, and taking it lying down," says Malik. "Rajani's solutions are too pat, but at least she shows you can shout." Now "Rajani" has consumer advocates rejoicing.

"This has been a godsend for us," says Pushpa Motwani, head of the Bombay-based Consumer Guidance Society of India, who immediately after the cooking-gas episode issued a press release supporting the show. Since "Rajani" started, Motwani says her average meeting attendance has gone from 50 people to 200.

Some women see the effect of "Rajani" as even more far-reaching in a country that for the most part still believes that wives should remain props in the background. "She's providing a catharsis for a number of women who are leading very repressed lives and who are not allowed to voice their opinions," says Meena Kaushik, a sociologist and market researcher who has interviewed women on their attitudes about the show. "I think she's a harbinger of change. Women see her as a Joan of Arc."

As it happens, this "Joan of Arc" is a former Air India flight attendant and restaurant hostess who says she is not at all like Rajani and is tired of the whole thing.

"I really want to opt out," says Priya Tendulkar, talking over tea in her Bombay flat one recent morning. "As an actress, I find it quite static. But it has become so successful that the makers want it to stay exactly the same way. It is suffocating at times."

She is wearing an outfit of tightly fitted pants, or churidars, with a matching tunic, or kurta, and a long, flowing scarf, or dupatt -- a traditional but stylish Indian ensemble that is still too modern for Rajani, who always wears saris and often keeps her long hair in a bun. "If Rajani had been a single woman with short hair, she wouldn't have been as successful," says Tendulkar. "A lot of men and women who write to me say what they like is the cozy family."

In person, Tendulkar is prettier and sweeter than the fuming Rajani, although she does have enough of a sense of personal injustice to complain about the money she says she is currently making, which is the equivalent of $200 per show. Like most unmarried Indian women, she lives with her parents -- her father is a successful playwright, her mother a former stage actress -- and already on this morning, the living room of the modest flat is filling up with members of the extended family: Tendulkar's hairdresser, a few servants here and there and autograph seekers at the door. Tendulkar ignores the commotion and continues her thoughts.

"Rajani never gets defeated," she says. "I feel at times that she should be confused, and stay like that for a day or two. I wish I could make her cry. She'd be more lifelike then. But I'm trapped in it now."

But the show's producer-director disagrees. "Rajani getting defeated defeats the purpose of the serial," says Basu Chatterji. "She must deliver the goods. That is the wish-fulfilment of the viewers. I'm tired too, but the nation has taken us up."

Tendulkar had left her Air India job ("I began to feel there was more to life than filling baby bottles and passing out liquor") and had begun acting in Hindi films when Chatterji, who had been inspired by the take-charge style of his own wife and daughter, offered her the part of Rajani that a more successful actress had already turned down. "It didn't sound very exciting to me," says Tendulkar, "although the role was very meaty."

"Rajani" didn't take off until the ninth episode, at the end of June, when Rajani discovered that unless she paid an illegal premium she would have to wait for days to get a new cooking-gas cylinder. Springing to action, she reported the incident to the police and had the agent arrested. Bombay gas distributors demonstrated in front of the television offices the same day. "It started a movement," says Tendulkar.

The success of Rajani is also the story of the growing influence of television in India. Indians now own about 5 million sets, twice as many as two years ago. Ten million sets are expected by 1987. The government estimates there are 10 viewers per television. It is only in the past year that the Doordarshan network has branched out from its characteristically deadly documentaries and tried what are called "sponsored programs" -- shows like "Rajani" and the popular soap opera "Hum Log" which are brought to the viewers by the makers of laundry detergent, refrigerators and instant coffee.

Rajiv Gandhi himself said recently that he enjoys "Rajani," and that it sets a good example for the Indian consumer. Now the newspapers are reporting incidents of Rajani-style behavior, like women standing up to rude taxi drivers, but most people aren't as successful in the real world. Rajani is viewed more as a superwoman who brings them courage, not results.

Everybody doesn't love Rajani, of course. Intellectuals complain that her targets are trivial, and that Rajani has yet to take on corrupt politicians, organized crime and the problems of the poor. Sociologist Meena Kaushik says upper-class women find her loudmouth style unsophisticated, and that young marrieds dislike the mouse she has for a husband.

"She's bringing out such strong emotions," Kaushik says. "People are not indifferent to her." Neither is the minister for information and broadcasting, who, after the taxi drivers' protest, announced that the government was behind Rajani and planned to continue it.

The government, however, censors the show as it sees fit. In one upcoming episode, Rajani was to have complained that a government commission appointed to study city potholes was "made up of four or five old men who are out of jobs." That went out.

"I had to redub it," Tendulkar says. "It will look very funny."

In the meantime, she keeps trying to tell people that she's Priya Tendulkar, not Rajani. "People are trying to make me into a cult figure," she complains. When she was in New Delhi for a press conference recently, a mix-up caused her to be half an hour late to meet with reporters. Rajani, late? The woman who is always lecturing people about promptness? The press was snarling when she got there.

"They tried to call me names," she says. "There was chaos. Thirty-five furious journalists. I really couldn't handle it. I thought I was going to cry. They were treating me like I'd committed murder. I thought I shouldn't cry in front of them, so the only thing to do was to get up and go." The press conference was over as soon as it started, and Tendulkar fled back to her room.

Rajani would have shown them.